WO2018052869A1

WO2018052869A1 - Glass manufacturing apparatus and methods

Info

Publication number: WO2018052869A1
Application number: PCT/US2017/051055
Authority: WO
Inventors: Pierre LARONZE; Christopher Myron SMITH
Original assignee: Corning Incorporated
Priority date: 2016-09-13
Filing date: 2017-09-12
Publication date: 2018-03-22
Also published as: JP2019526524A; CN109790056A; KR20190042742A; TW201827359A

Abstract

A glass manufacturing apparatus may include a portion of a conduit positioned within an internal bore of a refractory tube. In one embodiment, the refractory tube includes a first heating element operable to heat a first length of the refractory tube and a second heating element operable to heat a second length of the refractory tube. In another embodiment, a forming vessel includes an inlet and a lower end of the refractory device is positioned within the inlet. In further embodiments, methods of manufacturing glass include flowing molten material along the flow axis through the interior pathway of the conduit. In some embodiments, the method includes flowing molten material through an outlet of a downstream segment of a delivery pipe positioned within the inlet.

Description

GLASS MANUFACTURING APPARATUS AND METHODS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/393,759, filed on September 13, 2016, U.S. Provisional Application Serial No. 62/428,792, filed on December 01, 2016, and U.S. Provisional Application Serial No. 62/514, 118, filed on June 02, 2017, the contents of each are relied upon and incorporated herein by reference in their entireties.

FIELD

[0002] The present disclosure relates generally to methods and apparatus for manufacturing glass, and more particularly, to methods and apparatus for heating molten material within a conduit.

BACKGROUND

[0003] It is known to manufacture glass with a glass manufacturing apparatus. Typical glass manufacturing apparatus include pipes or conduits that convey molten material within the apparatus. For example, a glass manufacturing apparatus may include a delivery pipe that delivers molten material to an inlet of a forming vessel.

SUMMARY

[0004] The following presents a simplified summary of the disclosure in order to provide a basic understanding of some exemplary embodiments described in the detailed description.

[0005] In some embodiments, a glass manufacturing apparatus may include a refractory tube including a first heating element operable to heat a first length of the refractory tube and a second heating element operable to heat a second length of the refractory tube. The first heating element may be electrically isolated from the second heating element. In some embodiments, the apparatus may include a conduit positioned in an internal bore of the refractory tube. An outer surface of the conduit may face an inner surface of the internal bore along the first length and the second length, and an inner surface of the conduit may define an interior pathway extending along a flow axis of the conduit.

[0006] In some embodiments, the glass manufacturing apparatus may include a glass former to form a glass ribbon, where the glass former may include a forming vessel, the conduit may include a delivery pipe, and an outlet of the delivery pipe may extend into an inlet of the forming vessel.

[0007] In some embodiments, the delivery pipe may include an upstream segment positioned within the internal bore of the refractory tube, and a downstream segment protruding out of the internal bore from a lower end of the refractory tube.

[0008] In some embodiments, the inlet of the forming vessel may include an interior passage extending along an axis of the inlet. The interior passage can include an upper portion and a lower portion. The upper cross- sectional area of the upper portion of the interior passage taken perpendicular to the axis of the inlet may be larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis of the inlet. The lower end of the refractory tube may be positioned within the upper portion of the interior passage.

[0009] In some embodiments, the inner surface of the internal bore of the refractory tube can circumscribe the outer surface of the conduit along the flow axis.

[0010] In some embodiments, the first length of the refractory tube may be axially spaced apart from the second length of the refractory tube along the flow axis with an intermediate portion of the refractory tube axially positioned between the first length of the refractory tube and the second length of the refractory tube.

[0011] In some embodiments, the intermediate portion of the refractory tube may electrically isolate the first heating element from the second heating element.

[0012] In some embodiments, the first heating element may be mounted to the first length of the refractory tube and the second heating element may be mounted to the second length of the refractory tube.

[0013] In some embodiments, the inner surface of the conduit may have a circular cross-sectional profile perpendicular to the flow axis of the conduit. [0014] In some embodiments, a free end of the first heating element may extend from a first side of the refractory tube, and a free end of the second heating element may extend from a second side of the refractory tube. In some embodiments, the first side may be opposite the second side.

[0015] In some embodiments, the first heating element and the second heating element may be concentrically aligned along the axis of the refractory tube.

[0016] In some embodiments, the axis of the refractory tube and the flow axis of the conduit may be collinear.

[0017] In some embodiments, the first heating element may be wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element may be wound about the axis of the refractory tube along the second length of the refractory tube.

[0018] In some embodiments, at least one of the first heating element and the second heating element may be helically wound about the axis of the refractory tube.

[0019] In some embodiments, the first heating element may be seated within a first groove defined by an outer surface of the refractory tube, and the second heating element may be seated within a second groove defined by the outer surface of the refractory tube.

[0020] In some embodiments, the first groove and the second groove may be concentrically aligned along the axis of the refractory tube.

[0021] In some embodiments, the first groove may be spaced apart from the second groove along the axis of the refractory tube by an intermediate portion of the refractory tube axially positioned between the first groove and the second groove. The intermediate portion of the refractory tube may electrically isolate the first heating element from the second heating element.

[0022] In some embodiments, the glass manufacturing apparatus may include a layer of cement covering at least a portion of the outer surface of the refractory tube. The layer of cement may at least partially encapsulate the first heating element within the first groove and at least partially encapsulate the second heating element within the second groove. [0023] In some embodiments, at least one of the first heating element and the second heating element may include a plurality of heating elements. Each heating element of the plurality of heating elements may be operable to heat a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube. Each heating element of the plurality of heating elements may be electrically isolated from other heating elements of the plurality of heating elements.

[0024] In some embodiments, each heating element of the plurality of heating elements may be mounted to the respective circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube.

[0025] In some embodiments, the respective circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube may include a respective groove defined by an outer surface of the refractory tube. Each heating element of the plurality of heating elements may be seated within the respective groove.

[0026] In some embodiments, each circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube may be spaced apart from other circumferential portions of the corresponding plurality of circumferential portions with a respective channel portion of the refractory tube extending along an axis of the refractory tube and radially positioned between each circumferential portion.

[0027] In some embodiments, the respective channel portion of the refractory tube may electrically isolate each heating element of the plurality of heating elements.

[0028] In some embodiments, a free end of each heating element of the plurality of heating elements may extend within the respective channel portion of the refractory tube. [0029] In some embodiments, the first length of the refractory tube may be axially spaced apart from the second length of the refractory tube along the flow axis with an intermediate portion of the refractory tube axially positioned between the first length of the refractory tube and the second length of the refractory tube, and at least one of the respective channel portions of the refractory tube may extend along the axis of the refractory tube across the intermediate portion between the first length of the refractory tube and the second length of the refractory tube.

[0030] In some embodiments, a free end of at least one heating element of the plurality of heating elements of the second heating element may extend within the at least one of the respective channel portions of the refractory tube across the intermediate portion between the first length of the refractory tube and the second length of the refractory tube.

[0031] In some embodiments, the glass manufacturing apparatus may include a thermocouple positioned within at least one of the respective channel portions of the refractory tube.

[0032] In some embodiments, a portion of the thermocouple may extend from an outer surface of the refractory tube to the inner surface of the refractory tube.

[0033] In some embodiments, the glass manufacturing apparatus may include a sleeve circumscribing the conduit. An inner surface of the sleeve may be spaced a distance from the outer surface of the conduit thereby defining a space within which the refractory tube may be positioned. In some embodiments, the sleeve may include a flange that abuts the outer surface of the conduit thereby enclosing an end of the space.

[0034] In some embodiments, a glass manufacturing apparatus may include a refractory device including an internal bore. The glass manufacturing apparatus may include a delivery pipe including an upstream segment positioned within the internal bore and a downstream segment protruding out of the internal bore from a lower end of the refractory device. The glass manufacturing device may include a forming vessel including an inlet including an interior passage extending along an axis of the inlet. The interior passage may include an upper portion and a lower portion. An an upper cross- sectional area of the upper portion of the interior passage taken perpendicular to the axis may be larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis. The lower end of the refractory device may be positioned within the upper portion of the interior passage.

[0035] In some embodiments, the forming vessel may include molten material with a free surface positioned within the lower portion of the interior passage.

[0036] In some embodiments, the lower cross-sectional area may be substantially constant along an axial length of the lower portion of the interior passage.

[0037] In some embodiments, the downstream segment of the delivery pipe may include a free end positioned within the axial length of the lower portion of the interior passage.

[0038] In some embodiments, the lower end of the refractory device may include an outer periphery defining a cross-sectional footprint taken perpendicular to an axis of the delivery pipe. The cross-sectional footprint of the lower end of the refractory device may be greater than the lower cross-sectional area of the lower portion of the interior passage.

[0039] In some embodiments, the downstream segment of the delivery pipe may include a free end comprising an outer periphery defining a cross-sectional footprint taken perpendicular to the axis of the delivery pipe. The cross-sectional footprint of the free end of the delivery pipe may be smaller than the lower cross-sectional area of the lower portion of the interior passage.

[0040] In some embodiments, the upper portion of the interior passage may include an upper axial length along the axis of the inlet. The upper cross-sectional area of the upper portion may be substantially constant along the upper axial length.

[0041] In some embodiments, the upper portion of the interior passage may include a lower axial length. The upper cross-sectional area of the upper portion may be continuously reduced in size along the lower axial length in a downstream direction of the axis of the inlet.

[0042] In some embodiments, the upper portion of the interior passage may further include an upper axial length along the axis of the inlet. The upper cross-sectional area of the upper portion may be substantially constant along the upper axial length. The lower axial length may be positioned between the upper axial length and the lower portion of the interior passage.

[0043] In some embodiments, a method of manufacturing glass may include flowing molten material through an interior pathway defined by a conduit along a flow axis of the conduit, wherein the conduit is positioned in an internal bore of a refractory tube. The method may include heating the molten material within the conduit by heating a first length of the refractory tube with a first heating element and heating a second length of the refractory tube with a second heating element that may be electrically isolated from the first heating element.

[0044] In some embodiments, heating the molten material within the conduit may include heating a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube with at least one of a corresponding plurality of first heating elements and a corresponding plurality of second heating elements.

[0045] In some embodiments, each heating element of the corresponding plurality of first heating elements and each heating element of the corresponding plurality of second heating elements may be electrically isolated from other heating elements of the corresponding plurality of first heating elements and the corresponding plurality of second heating elements.

[0046] In some embodiments, the method may include measuring a temperature of the molten material within the conduit, and then operating at least one of the first heating element and the second heating element based on the measured temperature.

[0047] In some embodiments, the first heating element may be wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element may be would about the axis of the refractory tube along the second length of the refractory tube.

[0048] In some embodiments, at least one of the first heating element and the second heating element may be helically wound about the axis of the refractory tube. [0049] In some embodiments, the flow axis of the conduit may extend in the direction of gravity, and the flow axis of the conduit and an axis of the refractory tube may be collinear.

[0050] In some embodiments, the conduit may include a delivery pipe. The method may further include providing the heated molten material from the delivery pipe to an inlet of a forming vessel of a glass former and then forming a glass ribbon from the molten material with the glass former.

[0051] In some embodiments, the inlet of the forming vessel may include an interior passage extending along an axis of the inlet. The interior passage may include an upper portion and a lower portion. An upper cross- sectional area of the upper portion of the interior passage taken perpendicular to the axis may be larger than a lower cross- sectional area of the lower portion of the interior passage taken perpendicular to the axis. A lower end of the refractory tube may be positioned within the upper portion of the interior passage. A free surface of molten material of the glass former may be positioned within the lower portion of the interior passage.

[0052] In some embodiments, a minimum distance between the refractory tube and an inner surface of the inlet may be greater than or equal to 1.27 cm.

[0053] In some embodiments, methods of manufacturing glass with a delivery pipe are provided. The delivery pipe can include an upstream segment positioned within an internal bore of a refractory device and a downstream segment protruding out of the internal bore from a lower end of the refractory device. The lower end of the refractory device may be positioned within an interior passage of an inlet of a forming vessel. The method may include flowing molten material through an outlet of the downstream segment of the delivery pipe positioned within the interior passage of the inlet of the forming vessel to provide the forming vessel with a free surface of the molten material positioned within the interior passage of the inlet. The method may further include forming a glass ribbon from the molten material with the forming vessel.

[0054] In some embodiments, the method can further include heating the molten material within the delivery pipe by heating a first length of a refractory tube of the refractory device with a first heating element and heating a second length of the refractory tube with a second heating element that is electrically isolated from the first heating element.

[0055] In some embodiments, heating the molten material within the delivery pipe can include heating a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube with at least one of a corresponding plurality of first heating elements and a corresponding plurality of second heating elements.

[0056] In some embodiments, each heating element of the corresponding plurality of first heating elements and each heating element of the corresponding plurality of second heating elements may be electrically isolated from other heating elements of the corresponding plurality of first heating elements and the corresponding plurality of second heating elements.

[0057] In some embodiments, the method can further include measuring a temperature of the molten material within the delivery pipe, and then operating at least one of the first heating element and the second heating element based on the measured temperature.

[0058] In some embodiments, the first heating element may be wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element may be wound about the axis of the refractory tube along the second length of the refractory tube.

[0059] In some embodiments, at least one of the first heating element and the second heating element may be helically wound about the axis of the refractory tube.

[0060] In some embodiments, the molten material may flow along a flow axis of the delivery pipe to the outlet of the downstream segment. The flow axis extending in the direction of gravity, and the flow axis is collinear with an axis of a refractory tube of the refractory device.

[0061] In some embodiments, the interior passage of the inlet can extend along an axis of the inlet and the inlet can include an upper portion and a lower portion. An upper cross-sectional area of the upper portion of the interior passage taken perpendicular to the axis can be larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis. The lower end of the refractory device may be positioned within the upper portion of the interior passage. The free surface of molten material may be positioned within the lower portion of the interior passage.

[0062] In some embodiments, the downstream segment of the delivery pipe may include a free end including the outlet.

[0063] In some embodiments, the free end of the delivery pipe may be positioned within the lower portion of the interior passage.

[0064] In some embodiments, the free end of the delivery pipe may be positioned above the free surface of the molten material.

[0065] In some embodiments, the free end of the delivery pipe may be positioned below the free surface of the molten material.

[0066] In some embodiments, a minimum distance between the refractory device and an inner surface of the inlet may be greater than or equal to 1.27 cm.

[0067] The above embodiments are exemplary and may be provided alone or in any combination with any one or more embodiments provided herein without departing from the scope of the disclosure. Moreover, it is to be understood that both the foregoing general description and the following detailed description present embodiments of the present disclosure, and are intended to provide an overview or framework for understanding the nature and character of the embodiments as they are described and claimed. The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description, serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS [0068] These and other features, embodiments, and advantages of the present disclosure may be further understood when read with reference to the accompanying drawings:

[0069] FIG. 1 illustrates a schematic view of an exemplary glass manufacturing apparatus in accordance with embodiments of the disclosure;

[0070] FIG. 2 shows an enlarged cross-sectional view the glass manufacturing apparatus taken at view 2 of FIG. 1 including an exemplary conduit and an exemplary refractory tube;

[0071] FIG. 3 shows an enlarged cross-sectional view of a region of the exemplary conduit and the exemplary refractory tube taken at view 3 of FIG. 2;

[0072] FIG. 4 illustrates a schematic view of an exemplary refractory tube including a first heating element and a second heating element in accordance with embodiments of the disclosure;

[0073] FIG. 5 illustrates a schematic view of an alternate exemplary refractory tube including a first heating element and a second heating element in accordance with embodiments of the disclosure;

[0074] FIG. 6 illustrates a schematic view of the alternate exemplary refractory tube taken at line 6-6 of FIG. 5;

[0075] FIG. 7 illustrates a schematic view of the alternate exemplary refractory tube taken at line 7-7 of FIG. 5;

[0076] FIG. 8 illustrates an enlarged cross-sectional view of the glass manufacturing apparatus similar to FIG. 2 but illustrating an embodiment with a free end of the delivery pipe positioned below a free surface of molten material of a forming vessel;

[0077] FIG. 9 is a partial cross section of the glass manufacturing apparatus along line 9-9 of FIG. 8;

[0078] FIG. 10 illustrates an upper cross-sectional area of an upper portion of an interior passage of the inlet and a lower cross-sectional area of a lower portion of the interior passage of the inlet; and [0079] FIG. 11 illustrates a cross-sectional footprint of a lower end of a refractory device and a cross-sectional footprint of a free end of a downstream segment of the delivery pipe; and

[0080] FIG. 12 illustrates an enlarged cross-sectional view of the glass manufacturing apparatus similar to FIGS. 2 and 8 but illustrating an embodiment of the free end of the delivery pipe positioned within an upper portion of an interior passage of an inlet of the forming vessel.

DETAILED DESCRIPTION

[0081] Methods will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the disclosure are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0082] Glass sheets are commonly fabricated by flowing molten material to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming processes including, float, slot draw, down-draw (e.g., fusion down-draw), up-draw, press roll or any other forming processes. The glass ribbon from any of these processes may then be subsequently divided to provide one or more glass sheets suitable for further processing into a desired application, including but not limited to, a display application, a lighting application, a photovoltaic application or any other application benefiting from the use of high quality glass sheets. For example, the one or more glass sheets may be used in a variety of display applications, including liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), or the like.

[0083] FIG. 1 schematically illustrates an exemplary glass manufacturing apparatus 101 to process, manufacture, and form a glass ribbon 103. The glass manufacturing apparatus 101 may operate to provide a glass manufacturing process that may, in some embodiments, include any one or more of the features of the glass manufacturing apparatus 101 set forth in this disclosure. For illustration purposes, the glass manufacturing apparatus 101 and the glass manufacturing process are illustrated as a fusion down-draw apparatus and process, although other glass manufacturing apparatus and/or glass manufacturing processes including up-draw, float, press rolling, slot draw, etc. may be provided in some embodiments. As illustrated, the glass manufacturing apparatus 101 may include a melting vessel 105 oriented to receive batch material 107 from a storage bin 109. The batch material 107 may be introduced by a batch delivery device 111 powered by a motor 113. An optional controller 115 may be operated to activate the motor 113 such that the batch delivery device 111 may introduce a desired amount of batch material 107 into the melting vessel 105, as indicated by arrow 117. A glass melt probe 119 may be used to measure a level of molten material 121 within a standpipe 123 and communicate the measured information to the controller 115 by way of a communication line 125.

[0084] The glass manufacturing apparatus 101 may also include a fining vessel 127 located downstream from the melting vessel 105 relative to a flow direction of the molten material 121 and coupled to the melting vessel 105 by way of a first connecting conduit 129. In some embodiments, molten material 121 may be gravity fed from the melting vessel 105 to the fining vessel 127 by way of the first connecting conduit 129. For example, gravity may drive the molten material 121 through an interior pathway of the first connecting conduit 129 from the melting vessel 105 to the fining vessel 127. Within the fining vessel 127, bubbles may be removed from the molten material 121 by various techniques.

[0085] The glass manufacturing apparatus 101 may further include a mixing chamber 131 that may be located downstream from the fining vessel 127 relative to a flow direction of the molten material 121. In some embodiments, the mixing chamber 131 may include a shaft 150 including a plurality of protrusions 151 (e.g., stir blades) to mix molten material 121 within the mixing chamber 131. The mixing chamber 131 may be used to provide a homogenous composition of molten material 121, thereby reducing or eliminating inhomogeneity that may otherwise exist within the molten material 121 exiting the fining vessel 127. As shown, the fining vessel 127 may be coupled to the mixing chamber 131 by way of a second connecting conduit 135. In some embodiments, molten material 121 may be gravity fed from the fining vessel 127 to the mixing chamber 131 by way of the second connecting conduit 135. For instance, gravity may drive the molten material 121 through an interior pathway of the second connecting conduit 135 from the fining vessel 127 to the mixing chamber 131.

[0086] The glass manufacturing apparatus 101 may further include a delivery vessel 133 that may be located downstream from the mixing chamber 131 relative to a flow direction of the molten material 121. The delivery vessel 133 may condition the molten material 121 to be fed into a glass former 140. For example, the delivery vessel 133 may function as an accumulator and/or flow controller to adjust and provide a consistent flow of molten material 121 to the glass former 140. As shown, the mixing chamber 131 may be coupled to the delivery vessel 133 by way of a third connecting conduit 137. In some embodiments, molten material 121 may be gravity fed from the mixing chamber 131 to the delivery vessel 133 by way of the third connecting conduit 137. For instance, gravity may drive the molten material 121 through an interior pathway of the third connecting conduit 137 from the mixing chamber 131 to the delivery vessel 133

[0087] As further illustrated, a conduit, such as the illustrated delivery pipe 139, may be positioned to deliver molten material 121 to the glass former 140 of the glass manufacturing apparatus 101. The glass former 140 may draw the molten material 121 into the glass ribbon 103 from a bottom edge (e.g., root 145) of a forming vessel 143. In the illustrated embodiment, the forming vessel 143 may be provided with an inlet 141 oriented to receive molten material 121 from the delivery pipe 139 of the delivery vessel 133. In some embodiments, the forming vessel 143 may include a trough oriented to receive the molten material 121 from the inlet 141. The forming vessel 143 may further include a forming wedge including a pair of downwardly inclined converging surface portions extending between opposed ends of the forming wedge and joining at the root 145. In some embodiments, the molten material 121 may flow from the inlet 141 into the trough of the forming vessel 143. The molten material 121 may then overflow from the trough by simultaneously flowing over corresponding weirs and downward over the outer surfaces thereof. Respective streams of molten material 121 then flow along the downwardly inclined converging surface portions of the forming wedge to be drawn off the root 145 of the forming vessel 143, where the flows converge and fuse into the glass ribbon 103. The glass ribbon 103 may then be fusion drawn off the root 145 with a width "W" of the glass ribbon 103 extending between a first vertical edge 147a of the glass ribbon 103 and a second vertical edge 147b of the glass ribbon 103.

[0088] In some embodiments, a thickness of the glass ribbon 103 defined between a first major surface and an opposing second major surface of the glass ribbon 103 may be, for example, from about 40 micrometers (μπι) to about 3 millimeters (mm), for example, from about 40 micrometers to about 2 millimeters, for example, from about 40 micrometers to about 1 millimeter, for example, from about 40 micrometers to about to about 0.5 millimeters, for example, from about 40 micrometers to about 400 micrometers, for example, from about 40 micrometers to about 300 micrometers, for example, from about 40 micrometers to about 200 micrometers, for example, from about 40 micrometers to about 100 micrometers, or, for example, about 40 micrometers, although other thicknesses may be provided in further embodiments. In addition, the glass ribbon 103 may include a variety of compositions including but not limited to glass (e.g., soda-lime glass, borosilicate glass, alumino-borosilicate glass, an alkali-containing glass, an alkali- free glass), ceramic, glass-ceramic, or any combination thereof.

[0089] In some embodiments, the glass manufacturing apparatus 101 may include a glass separator 149. As shown, the glass separator 149 may be positioned downstream from the glass former 140 and oriented to separate the glass sheet 104 from the glass ribbon 103. A variety of glass separators 149 may be provided in embodiments of the present disclosure. For example, a traveling anvil machine may be provided that may score and then break the glass ribbon 103 along the score line. In some embodiments, the glass separator 149 may include a laser, a scribe, a tool, a robot, etc. that may operate to separate the glass sheet 104 from the glass ribbon 103 along a separation path parallel to the width "W" of the glass ribbon 103 between the first vertical edge 147a of the glass ribbon 103 and the second vertical edge 147b of the glass ribbon 103.

[0090] It is to be understood that features of the present disclosure may be employed to heat molten material 121 within a conduit, including one or more conduits that may convey molten material 121 within the glass manufacturing apparatus 101. For example, in some embodiments, the conduit may include, but not be limited to, one or more of the first connecting conduit 129, the second connecting conduit 135, the third connecting conduit 137, and the delivery pipe 139. Likewise, in some embodiments, the conduit may include one or more conduits not explicitly disclosed in the present disclosure. Accordingly, for purposes of explanation and not limitation, unless otherwise noted, an exemplary conduit to heat molten material 121 will be described with respect to the delivery pipe 139, with the understanding that, in some embodiments, the same or similar features may be employed to heat molten material 121 within one or more conduits that convey molten material 121 within the glass manufacturing apparatus 101 without departing from the scope of the disclosure.

[0091] As illustrated in FIG. 2, which shows an enlarged view of the glass manufacturing apparatus 101 identified by numeral 2 of FIG. 1, in some embodiments, the glass manufacturing apparatus 101 may include a refractory device 198 that can include a refractory tube 200. In some embodiments, the refractory tube may be made from a material that helps control heat transfer from a conduit (e.g., the illustrated delivery pipe 139) to help maintain the molten material 121 being conveyed through the delivery pipe 139 at a desired temperature. Although not required, some embodiments of the refractory device 198 throughout the disclosure may include a heating device and/or a cooling device to facilitate transfer of heat to or from the molten material 121 depending on the particular application. For instance, as shown, the refractory tube 200 can include a first heating element 210 operable to heat a first length 201 of the refractory tube 200 and a second heating element 220 operable to heat a second length 202 of the refractory tube 200. Throughout the disclosure, each of the first length 201 and the second length 202 of the refractory tube 200 is considered to be a length of the refractory tube 200 along a flow axis 180 of the delivery pipe 139. As shown in the embodiment illustrated in FIG. 2, the first length 201 of the refractory tube 200 may include an axial segment (e.g., circular cylindrical segment) of the refractory tube 200 along the flow axis 180 of delivery pipe 139 while the second length 202 of the refractory tube 200 may include another axial segment (e.g., circular cylindrical segment) of the refractory tube 200 along the flow axis 180 of the delivery pipe 139. As further illustrated, in some embodiments, the first length 201 of the refractory tube 200 may be positioned upstream relative to the second length 202 of the refractory tube 200 relative to a flow direction 184 of molten material 121 passing through an interior pathway 175 of the delivery pipe 139. In some embodiments, the flow direction 184 of the molten material 121 may be in the same direction as the flow axis 180. For example, as shown, the flow direction 184 of the molten material 121 may be in the same direction as the illustrated linear flow axis 180. Furthermore, in some embodiments, the linear flow axis 180 may be in the same direction as the illustrated direction of gravity "g," and the flow direction 184 of the molten material 121 may therefore be in the same direction as the direction of gravity "g."

[0092] In some embodiments, the first heating element 210 may be mounted to the first length 201 of the refractory tube 200 and the second heating element 220 may be mounted to the second length 202 of the refractory tube 200. In some embodiments, each of the first heating element 210 and the second heating element 220 may convert electrical energy to heat when an electric current supplied from a power source (e.g., respective first power source 401, second power source 402, illustrated in FIG. 4) is provided to the respective heating element. For example, in some embodiments, each of the first heating element 210 and the second heating element 220 may be an electrical resistor which converts an electric current passing through the electrical resistor into heat energy based at least on the principle of Joule heating. In some embodiments, at least one of the first heating element 210 and the second heating element 220 may include one or more of a wire, ribbon, strip, and foil. In addition, in some embodiments, at least one of the first heating element 210 and the second heating element 220 may include (e.g., be manufactured from) one or more of a metal material (e.g., platinum, platinum alloy), a ceramic material, and a polymer material. In some embodiments, the first heating element 210 may provide (e.g., transfer) heat from the first heating element 210 to the first length 201 of the refractory tube 200, thereby increasing a temperature of the first length 201 of the refractory tube 200, based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the first heating element 210 and the first length 201 of the refractory tube 200. Likewise, in some embodiments the second heating element 220 may provide (e.g., transfer) heat from the second heating element 220 to the second length 202 of the refractory tube 200, thereby increasing a temperature of the second length 202 of the refractory tube 200, based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the second heating element 220 and the second length 202 of the refractory tube 200.

[0093] In some embodiments, the first heating element 210 may be electrically isolated from the second heating element 220. Electrically isolating the first heating element 210 from the second heating element 220 may prevent arcing of an electric current between the first heating element 210 and the second heating element 220. In some embodiments, electrically isolating the first heating element 210 from the second heating element 220 may include positioning the first heating element 210 a predetermined distance (e.g., distance 216, shown in FIG. 3) away from the second heating element 220 where the distance 216 is selected such that an electric current cannot arc between the first heating element 210 and the second heating element 220 across the distance 216. In some embodiments, electrically isolating the first heating element 210 from the second heating element 220 may include providing an electrically non-conductive material between the first heating element 210 and the second heating element 220 that prevents arcing of electric current between the first heating element 210 and the second heating element 220. Accordingly, in some embodiments, the first heating element 210 and the second heating element 220 may be independently operated to selectively heat the respective first length 201 and second length 202 of the refractory tube 200. Conversely, for example, if the first heating element 210 was not electrically isolated from the second heating element 220, in some embodiments, arcing of an electric current between the first heating element 210 and the second heating element 220 could occur. Electric arcing between the first heating element 210 and the second heating element 220 may interfere with independent operation of the first heating element 210 and the second heating element 220 thereby prohibiting selective heating of a respective length of the refractory tube 200. Accordingly, electrically isolating the first heating element 210 from the second heating element 220 may provide refined, independent temperature control of two or more lengths of the refractory tube 200 as compared to heating the refractory tube 200 with a single heating element or with multiple heating elements that are not electrically isolated from each other. That is, heating the refractory tube 200 with a single heating element or with multiple heating elements that are not electrically isolated from each other may provide less refined temperature control where only a single length of the refractory tube 200 or only the entire refractory tube 200, for example, may be heated.

[0094] In some embodiments, the delivery pipe 139 may be positioned in an internal bore of the refractory device 198 such an internal bore 205 of the refractory tube 200. In some embodiments, an outer surface 176 of the delivery pipe 139 may face an inner surface 204 of the internal bore 205 along the first length 201 of the refractory tube 200 and along the second length 202 of the refractory tube 200. In some embodiments, the outer surface 176 of the delivery pipe 139 may be in physical contact with the inner surface 204 of the internal bore 205 of the refractory tube 200. Alternatively, as shown in FIGS. 2 and 3, in some embodiments, the outer surface 176 of the delivery pipe 139 may be spaced a distance from the inner surface 204 of the internal bore 205 of the refractory tube 200 to provide a clearance between the delivery pipe 139 and the inner surface 204 of the internal bore 205 of the refractory tube 200. Providing a clearance between the outer surface 176 of the delivery pipe 139 and the inner surface 204 of the internal bore 205 of the refractory tube 200 may permit selective placement (e.g., at least one of insertion and removal) of the delivery pipe 139 into the internal bore 205 of the refractory tube 200 and may also accommodate dimensional changes of the delivery pipe 139 and the refractory tube 200 based at least on, for example, manufacturing tolerances and thermal expansion and contraction of at least one of the delivery pipe 139 and the refractory tube 200.

[0095] In some embodiments, an inner surface 174 of the delivery pipe 139 may define an interior pathway 175 extending along the flow axis 180 of the delivery pipe 139. In some embodiments, the delivery pipe 139 may therefore direct a flow of molten material 121 through the interior pathway 175 along the flow direction 184 of the flow axis 180. Thus, the interior pathway 175 of the delivery pipe 139 may extend along the flow axis 180 of the delivery pipe 139, and the flow axis 180 may extend between an inlet 181 of the delivery pipe 139 and an outlet 182 of the delivery pipe 139. In some embodiments, the flow axis 180 may define a linear flow path; however, in some embodiments, the flow axis 180 may define a non-linear flow path. In some embodiments, the flow axis 180 of the delivery pipe 139 may extend in the direction of gravity "g". In some embodiments, the inner surface 174 of the delivery pipe 139 may have a circular cross-sectional profile taken perpendicular to the flow axis 180 of the delivery pipe 139; however, in some embodiments, the inner surface 174 of the delivery pipe 139 may have a cross-sectional profile of a polygonal, elliptical or other shape taken perpendicular to the flow axis 180 of the delivery pipe 139. In some embodiments, providing the inner surface 174 of the delivery pipe 139 with a circular cross-sectional profile perpendicular to the flow axis 180 of the delivery pipe 139 may facilitate uniform heating of the molten material 121 within the delivery pipe 139 based on uniform transfer of heat from the refractory tube 200 to the delivery pipe 139.

[0096] Additionally, in some embodiments, providing the inner surface 174 of the delivery pipe 139 with a circular cross-sectional profile taken perpendicular to the flow axis 180 of the delivery pipe 139 may facilitate uniform flow of the molten material 121 within the interior pathway 175 of the delivery pipe 139 along the flow axis 180. For example, as shown in FIG. 2, in some embodiments the outlet 182 of the delivery pipe 139 may extend into the inlet 141 of the forming vessel 143 of the glass former 140, and the delivery pipe 139 may provide the molten material 121 to the inlet 141 of the forming vessel 143. In some embodiments, the inlet 141 of the forming vessel 143 may include a liner 142 that may withstand high temperatures, resist corrosion, and maintain structural integrity when exposed to molten material 121. For example, in some embodiments, the forming vessel 143 may be manufactured from a refractory material and the liner 142 may be manufactured from a precious metal (e.g., platinum, platinum-rhodium, etc.) to protect the refractory material from being in direct contact with the molten material 121 at the inlet 141 of the forming vessel 143. In some embodiments, the inlet 141 of the forming vessel 143 may include a free surface 122 of molten material 121 onto which molten material 121 from the outlet 182 of the delivery pipe 139 may be provided. In some embodiments, the delivery pipe 139 may extend into the inlet 141 of the forming vessel 143 and may penetrate the free surface 122 of the molten material 121. Accordingly, in some embodiments, the delivery pipe 139 may provide molten material 121 from the outlet 182 of the delivery pipe 139 to the inlet 141 of the forming vessel 143 at an elevation below the free surface 122 of the molten material 121. Alternatively, as shown in FIG. 2, the outlet 182 of the delivery pipe 139 may be positioned at a higher elevation than the free surface 122 of the molten material 121.

[0097] It is to be understood that, in some embodiments, at least one of the inlet 181 of the delivery pipe 139 and the outlet 182 of the delivery pipe 139 may define an outermost end of the delivery pipe 139 where molten material 121 may enter the delivery pipe 139 at the inlet 181, flow along the flow direction 184 of the flow axis 180 within the interior pathway 175 of the delivery pipe 139 from the inlet 181 to the outlet 182, and then exit the delivery pipe 139 at the outlet 182. In some embodiments, however, at least one of the inlet 181 of the delivery pipe 139 and the outlet 182 of the delivery pipe 139 may define an intermediate location along the delivery pipe 139 that is not an outermost end. Accordingly, in some embodiments, molten material 121 may enter the delivery pipe 139 at a first outermost end of the delivery pipe 139 upstream from the inlet 181 along the flow axis 180 relative to the flow of molten material 121, flow along the flow axis 180 within the interior pathway 175 of the delivery pipe 139 from the inlet 181 to the outlet 182, and then exit the delivery pipe 139 at a second outermost end of the delivery pipe 139 downstream from the outlet 182 along the flow axis 180 relative to the flow of molten material 121. In some embodiments, the inner surface 204 of the internal bore 205 of the refractory tube 200 may circumscribe the outer surface 176 of the delivery pipe 139 along the flow axis 180. In some embodiments, the inner surface 204 of the internal bore 205 may be continuous and may circumscribe the outer surface 176 of the delivery pipe 139 along the flow axis 180 at an axially location positioned between the inlet 181 of the delivery pipe 139 and the outlet 182 of the delivery pipe 139.

[0098] In some embodiments, the first length 201 of the refractory tube 200 may be defined along the flow axis 180 of the delivery pipe 139 between the inlet 181 of the delivery pipe 139 and an intermediate portion 215 of the refractory tube 200, and the second length 202 of the refractory tube 200 may be defined along the flow axis 180 of the delivery pipe 139 between the intermediate portion 215 of the refractory tube 200 and the outlet 182 of the delivery pipe 139. For example, in some embodiments, the first length 201 of the refractory tube 200 may be axially spaced apart from the second length 202 of the refractory tube 200 along the flow axis 180 with the intermediate portion 215 of the refractory tube 200 axially positioned between the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. In some embodiments, the first length 201 of the refractory tube 200 may provide (e.g., transfer) heat from the first length 201 to the delivery pipe 139 based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the first length 201 of the refractory tube 200 and the delivery pipe 139. Providing heat to the delivery pipe 139 may increase a temperature of the delivery pipe 139 and a temperature of the molten material 121 within the delivery pipe 139. Likewise, in some embodiments the second length 202 of the refractory tube 200 may provide (e.g., transfer) heat from the second length 202 to the delivery pipe 139 based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the second length 202 of the refractory tube 200 and the delivery pipe 139 in a region of the delivery pipe 139 corresponding to the first length 201 of the refractory tube 200. Providing heat to the delivery pipe 139 from the second length 202 of the refractory tube 200 may increase a temperature of the delivery pipe 139 and a temperature of the molten material 121 within the delivery pipe 139 in a region of the delivery pipe 139 corresponding to the second length 202 of the refractory tube 200. Accordingly, features of the present disclosure may selectively and independently control a temperature of molten material 121 within one or more regions of the delivery pipe 139.

[0099] Referring back to FIG. 1, in some embodiments, the delivery pipe 139 may be oriented to provide molten material 121 to the forming vessel 143 of the glass former 140, and the glass former 140 may form the glass ribbon 103 from the molten material 121. In some embodiments, the glass ribbon 103 may be formed at a rate corresponding to a mass or weight of glass formed per unit time, representing the flowrate of the molten material 121 in the glass manufacturing process. For example, in some embodiments, the flowrate of the molten material 121 flowing from the glass former 140 (e.g., flowing off of the root 145 of the forming vessel 143) and being formed into the glass ribbon 103 may define the flowrate of molten material 121 in the glass manufacturing process. In some embodiments, one or more factors may contribute to the flowrate of the molten material 121 flowing from the glass former 140. For example, the flowrate of the molten material 121 may be based at least in part on a viscosity of the molten material 121. In addition, the viscosity of the molten material 121 may be based at least in part on the temperature of the molten material 121 as well as a material composition of the molten material 121. In some embodiments, less viscous molten material 121 may provide a higher flowrate of molten material 121 than, for example, more viscous molten material 121, which may provide a comparatively lower flowrate of molten material 121. Accordingly, by controlling the temperature of the molten material 121, the features of the present disclosure may control the viscosity of the molten material 121. Additionally, by controlling the viscosity of the molten material 121, the features of the present disclosure may control the flowrate of the molten material 121 flowing, for example, from the glass former 140.

[00100] In some embodiments, controlling the temperature of molten material 121 in the glass manufacturing process may control characteristics of the glass ribbon 103. For example, controlling the temperature (and, in turn, the viscosity and the flowrate) of molten material 121 at the glass former 140 may control any one or more of a thickness of the glass ribbon 103, a width "W" of the glass ribbon 103, a variation in thickness across the width "W" of the glass ribbon 103, a temperature of the glass ribbon 103, a stress in the glass ribbon 103, an optical quality of the glass ribbon 103, as well as other parameters and attributes of the glass ribbon 103. In some embodiments, a consistent (e.g., constant) flowrate of molten material 121 at the glass former 140 over a period of time may provide a glass ribbon 103 having a uniform thickness that includes less stress concentrations than, for example, a glass ribbon 103 formed with molten material 121 flowing at an inconsistent (e.g., fluctuating, changing) flowrate over the same period of time. Accordingly, in some embodiments, changes in flowrate of molten material 121 at the glass former 140 may impact quality characteristics of the glass ribbon 103, and controlling the flowrate of molten material 121 at the glass former 140 may reduce undesirable characteristics of the glass ribbon 103 and improve the quality of the glass ribbon 103.

[00101] In some embodiments, as illustrated in FIG. 2, the interior pathway 175 of the delivery pipe 139 may be entirely occupied with molten material 121, in some embodiments, and the inner surface 174 of the delivery pipe 139 may abut (e.g., contact) molten material 121 around an entire periphery of the interior pathway 175. In some embodiments, controlling the temperature of the molten material 121 in the delivery pipe 139 may adjust the flowrate of the molten material 121 at the glass former 140. For example, increasing the temperature of the molten material 121 at in the delivery pipe 139 may decrease the viscosity of the molten material 121 and, in turn, increase the flowrate of the molten material 121 at the glass former 140. Conversely, decreasing the temperature of the molten material 121 in the delivery vessel 133 may increase the viscosity of the molten material 121, and, in turn, decrease the flowrate of the molten material 121 at the glass former 140.

[00102] Moreover, it has been observed that variability of the flowrate of the molten material 121 may increase as the flowrate itself increases. That is, for comparatively lower flowrates, the variability of the flowrate has been observed to be less; whereas, for comparatively higher flowrates, the variability of the flowrate has been observed to be greater. Thus, because greater variability of the flowrate of the molten material 121 at the glass former 140 may cause greater variability of any one or more of a thickness of the glass ribbon 103, a width "W" of the glass ribbon 103, a variation in thickness across the width "W" of the glass ribbon 103, a temperature of the glass ribbon 103, a stress in the glass ribbon 103, an optical quality of the glass ribbon 103, as well as other parameters and attributes of the glass ribbon 103, higher flowrates may exacerbate this correlation and, without the temperature control provided by the disclosure, may result in increasingly poorer quality glass ribbon 103. Accordingly, in addition to improving the quality of the glass ribbon 103 produced at the flowrate, the features of the present disclosure may also be employed in a glass manufacturing apparatus 101 to provide higher (e.g., increased) flowrates of the glass manufacturing process. Increased flowrates may result in higher output of glass ribbon 103 over a comparable time, thus decreasing costs and improving process efficiency.

[00103] In some embodiments, the delivery pipe 139 may be manufactured from a precious metal, for example, platinum, platinum alloy (e.g., platinum-rhodium), etc. that may withstand high temperatures, resist corrosion, and maintain structural integrity when exposed to molten material 121. In some embodiments, the refractory tube 200 may be manufactured from ceramic, alumina, and any other refractory material. Furthermore, such refractory material may be selected to be electrically non-conductive and thermally conductive in some embodiments including the heating elements 210, 220. In some embodiments, at least one of the first heating element 210 and the second heating element 220 may be manufactured from metal (e.g., a precious metal such as platinum , platinum-rhodium or other platinum alloy) that is electrically and thermally conductive and can maintain structural integrity under relatively high temperature conditions. Additionally, in some embodiments, a size (e.g., diameter) of the heating element and a length of the heating element may be selected to provide the heating element with a predetermined power (e.g., heat) output when an electric current is applied to the heating element. In some embodiments, the first heating element 210 may include a different power output than the second heating element 220; however, in some embodiments, the first heating element 210 may include the same power output as the second heating element 220. Providing the first heating element 210 and the second heating element 220 with different power outputs may heat the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 to different temperatures. Accordingly, the molten material 121 within the delivery pipe 139 may, likewise, be heated to different temperatures corresponding to the different temperatures of the first length 201 and the second length 202.

[00104] As shown in FIG. 4, in some embodiments, the first heating element 210 may be wound about an axis 280 of the refractory tube 200 along the first length 201 of the refractory tube 200, and the second heating element 220 may be wound about the axis 280 of the refractory tube 200 along the second length 202 of the refractory tube 200. For example, in some embodiments, at least one of the first heating element 210 and the second heating element 220 may be helically wound about the axis 280 of the refractory tube 200. In some embodiments, the axis 280 of the refractory tube 200 and the flow axis 180 of the delivery pipe 139 may be collinear; however, in some embodiments, the axis 280 of the refractory tube 200 and the flow axis 180 of the delivery pipe 139 may be parallel and located at different spatial coordinates. Additionally, in some embodiments, the axis 280 of the refractory tube 200 and the flow axis 180 of the delivery pipe 139 may extend at a non-zero angle relative to each other. In some embodiments, the first heating element 210 and the second heating element 220 may be concentrically aligned along the axis 280 of the refractory tube 200. Accordingly, in some embodiments, the first heating element 210 and the second heating element 220 may uniformly heat the respective first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. For example, collinearly aligning the axis 280 of the refractory tube 200 and the flow axis 180 of the delivery pipe 139 with the first heating element 210 and the second heating element 220 concentrically aligned along the axis 280 of the refractory tube 200 may provide uniform heating of the molten material 121 within the delivery pipe 139 flowing along the flow axis 180 of the delivery pipe 139.

[00105] In some embodiments, the outer surface 240 of the refractory tube

200 may include a first groove 209 and a second groove 219. As shown in FIG. 4, in some embodiments, the first groove 209 and the second groove 219 may be helically wound about the axis 280 of the refractory tube 200 with the first heating element 210 seated within the first helical groove 209 and the second heating element 220 seated within the second helical groove 219. In some embodiments, the first groove 209 and the second groove 219 may be concentrically aligned along the axis 280 of the refractory tube 200. Concentrically aligning the first groove 209 and the second groove 219 along the axis 280 of the refractory tube 200 may facilitate uniform heating of the molten material 121 within the delivery pipe 139 flowing along the flow axis 180 of the delivery pipe 139. For example, the first heating element 210 and the second heating element 220 may be respectively positioned (e.g., seated) within the concentrically aligned first groove 209 and the second groove 219 and may therefore uniformly heat the respective first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 thereby providing uniform heat to the molten material 121 within the delivery pipe 139

[00106] In some embodiments, the first groove 209 may be spaced apart from the second groove 219 along the axis 280 of the refractory tube 200 by the intermediate portion 215 of the refractory tube 200. For example, the intermediate portion 215 of the refractory tube 200 may be axially positioned between the first groove

209 and the second groove 219 to electrically isolate the first heating element 210 from the second heating element 220. In some embodiments, the refractory tube 200 including the first length 201 and the second length 202 may be manufactured from a single piece of refractory material. Manufacturing the refractory tube 200 from a single piece of refractory material may provide easier and/or better alignment of the first heating element

210 relative to the second heating element 220 and may therefore provide a more uniform heat distribution to the molten material 121 within the delivery pipe 139. For example, by manufacturing the refractory tube 200 from a single piece of refractory material, a positional relationship between the first groove 209 and the second groove 219 and the first heating element 210 positioned in the first groove 209 and the second heating element 220 positioned in the second groove 219 may be fixed. For example, if the first length 201 of the refractory tube 200 was physically separate from the second length 202 of the refractory tube 200 misalignment of the first heating element 210 and the second heating element 220 could occur when the first length 201 and the second length 202 are employed to provide heat to the delivery pipe 139. That is, the physically separate first length 201 of the refractory tube 200 may be stacked on top of the physically separate second length 202 of the refractory tube 200 and the concentricity of the first heating element 210 and the second heating element 220 may be misaligned based at least on the potential misalignment of the first length 201 and the second length 202.

[00107] Accordingly features of the present disclosure may facilitate alignment of the first heating element 210 and the second heating element 220 thereby providing better uniform heat transfer from the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 to the delivery pipe 139. Moreover, it is to be understood that, in some embodiments the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 may be manufactured from a plurality of pieces of refractory material without departing from the scope of the disclosure. For example, in some embodiments, the intermediate portion 215 of the refractory tube 200 between the first length 201 and the second length 202 may include a mechanical joint, an adhesive, a bonding agent, etc. that may connect the first length 201 of the refractory tube 200 to the second length 202 of the refractory tube 200 facilitating alignment of the first heating element 210 and the second heating element 220 as provided by the disclosure.

[00108] As schematically shown in FIG. 4, in some embodiments, a first power source 401 may provide electric current to the first heating element 210. Additionally, in some embodiments, the power sources 401, 402 may communicate with any one or more controllers and control devices (e.g., programmable logic controller) configured to (e.g., "programmed to", "encoded to", designed to", and/or "made to") operate to control the power sources 401, 402 in accordance with any one or more methods of the present disclosure. Although illustrated as separate power sources 401, 402, it is to be understood that, in some embodiments, a single power source may selectively provide electric current to the first heating element 210 and the second heating element 220. Additionally, in some embodiments, a free end 211 of the first heating element 210 may extend from a first side 212 of the refractory tube 200, and a free end 221 of the second heating element 220 may extend from a second side 222 of the refractory tube 200. In some embodiments, the first side may be opposite the second side to reduce the potential for electric arcing between the first heating element 210 and the second heating element 220. Referring back to FIG. 3, in some embodiments, the first heating element 210 may be spaced apart from the second heating element 220 by a distance 216 defined at least in part by the intermediate portion 215 of the refractory tube 200. Spacing the first heating element 210 the distance 216 apart from the second heating element 220 may electrically isolate the first heating element 210 from the second heating element 220. Additionally, because the intermediate portion 215 of the refractory tube 200 between the first length 201 and the second length 202 may be electrically non-conductive, the intermediate portion 215 of the refractory tube 200 may also electrically isolate the first heating element 210 from the second heating element 220.

[00109] Additionally, in some embodiments, the glass manufacturing apparatus 101 may include a layer of cement 250 applied to at least a portion of the outer surface 240 of the refractory tube 200 to cover the portion of the outer surface 240. For example, in some embodiments, the first helical groove 209 and the second helical groove 219 may be defined by the outer surface 240 of the refractory tube 200. In some embodiments, the layer of cement 250 may be applied to the outer surface 240 of the refractory tube 200 to at least partially encapsulate the first heating element 210 within the first groove 209 and to at least partially encapsulate the second heating element 220 within the second groove 219. In some embodiments, the layer of cement 250 may include an alumina cement or other electrically non-conductive material that may electrically isolate the first heating element 210 within the first groove 209 and the second heating element 220 within the second groove 219. For example, the cement 250 may be provided within the first groove 209 and the second groove 219 to at least partially encapsulate the respective first heating element 210 and the second heating element 220 thereby electrically isolating the first heating element 210 from the second heating element 220. In some embodiments, the layer of cement 250 may extend outward from the outer surface 240 of the refractory tube 200 to electrically isolate the outer surface 240 of the refractory tube 200. Electrically isolating the outer surface 240 of the refractory tube 200 with the layer of cement 250 may help prevent electric arcing between the first heating element 210 and the second heating element 220 and may also help prevent electric arcing between at least one of the first heating element 210 and the second heating element 220 and other electrically-conductive components within the glass manufacturing apparatus 101. Moreover, in some embodiments, electrically isolating the outer surface 240 of the refractory tube 200 with the layer of cement 250 may prevent electric arcing between at least one of the first heating element 210 and the second heating element 220 and a user who may install or service the refractory tube 200.

[00110] An alternate exemplary embodiment of the glass manufacturing apparatus 101 is illustrated in FIG. 5, with an exemplary first side view of the alternate exemplary embodiment of the glass manufacturing apparatus 101, taken along line 6-6 of FIG. 5, shown in FIG. 6 and an exemplary second side view of the alternate exemplary embodiment of the glass manufacturing apparatus 101, taken along line 7-7 of FIG. 5, shown in FIG. 7. As shown in FIG. 5, in some embodiments, at least one of the first heating element 210 and the second heating element 220 may be seated within respective first grooves 209 and respective second grooves 219 that wind back and forth relative to the axis 280 of the refractory tube 200 in a circumferential pattern on the corresponding first length 201 of the refractory tube 200 and the corresponding second length 202 of the refractory tube 200.

[00111] In some embodiments, the free end 211 of the first heating element 210 may extend from the first side 212 of the refractory tube 200 to connect to the first power source 401, and the free end 221 of the second heating element 220 may extend from the second side 222 of the refractory tube 200, that is opposite the first side 212, to connect to the second power source 402. In some embodiments, the free end 221 of the second heating element 220 may also extend from the second length 202 of the refractory tube 200 across the intermediate portion 215 of the refractory tube 200 into the first length 201 of the refractory tube 200. By extending from the second length 202 of the refractory tube 200 into the first length 201 of the refractory tube 200, in some embodiments, the free end 221 of the second heating element 220 may be positioned in a more accessible location to, for example, connect the free end 221 to the second power source 402. That is, for example, if the free end 221 of the second heating element 220 was to terminate within the second length 202 of the refractory tube 200, and therefore not extend into the first length 201 of the refractory tube 200, it may be difficult to connect the free end 221 of the second heating element 220 to the second power source 402 when the refractory tube 200 is positioned in or near the inlet 141 of the glass former 140, as shown in FIG. 2. Likewise, as discussed more fully below, a thermocouple lead 501 may extend from the second length 202 of the refractory tube 200 into the first length 201 of the refractory tube 200 to position the thermocouple lead 501 in a more accessible location to, for example, connect the thermocouple lead 501 to a controller (not shown) to at least one of record and monitor a temperature measured by a thermocouple 500 (shown in FIG. 7) that is connected to the thermocouple lead 501.

[00112] Additionally, as shown in FIGS. 6 and 7, in some embodiments, at least one of the first heating element 210 and the second heating element 220 may include a plurality of heating elements. For example, in some embodiments, the first heating element 210 may include a plurality of first heating elements 210a, 210b. Likewise, in some embodiments, the second heating element 220 may include a plurality of second heating elements 220a, 220b. In some embodiments, each heating element of the plurality of heating elements may be operable to heat a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. For example, in some embodiments, the first heating elements 210a, 210b may be operable to heat a respective circumferential portion 201a, 201b of the first length 201 of the refractory tube 200. Similarly, in some embodiments, the second heating elements 220a, 220b may be operable to heat a respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200.

[00113] In some embodiments, each heating element 210a, 210b of the plurality of first heating elements and each heating element 220a, 220b of the plurality of second heating elements may convert electrical energy to heat when an electric current supplied from a power source (e.g., respective first power sources 401a, 401b, illustrated in FIG. 6, and respective second power sources 402a, 402b, illustrated in FIG. 7) is provided to the respective heating elements. In some embodiments, each heating element 210a, 210b of the first plurality of heating elements may provide (e.g., transfer) heat from the first heating elements 210a, 210b to respective circumferential portion 201a, 201b of the first length 201 of the refractory tube 200, thereby increasing a temperature of the respective circumferential portion 201a, 201b of the first length 201 of the refractory tube 200, based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the first heating elements 210a, 210b and the respective circumferential portion 201a, 201b of the first length 201 of the refractory tube 200. Likewise, in some embodiments the second heating elements 220a, 220b may provide (e.g., transfer) heat from the second heating elements 220a, 220b to the respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200, thereby increasing a temperature of the respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200, based on at least one of thermal conduction, thermal convection, and thermal radiation heat transfer between the second heating elements 220a, 220b and the respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200.

[00114] As schematically shown in FIG. 6, in some embodiments, the first power sources 401a, 401b may provide electric current to the respective heating elements 210a, 210b of the plurality of first heating elements. Likewise, as schematically shown in FIG. 7, in some embodiments, the second power sources 402a, 402b may provide electric current to the respective heating elements 220a, 220b of the plurality of second heating elements. Additionally, in some embodiments, the power sources 401a, 401b, 402a, 402b may communicate with any one or more controllers and control devices (e.g., programmable logic controller) configured to (e.g., "programmed to", "encoded to", designed to", and/or "made to") operate to control the power sources 401a, 401b, 402a, 402b in accordance with any one or more methods of the present disclosure. Although illustrated as separate power sources 401a, 401b, 402a, 402b it is to be understood that, in some embodiments, a single power source may selectively provide electric current to one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements.

[00115] In some embodiments, each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may be mounted to the respective circumferential portion 201a, 201b, 202a, 202b of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. In some embodiments, the respective circumferential portion 201a, 201b, 202a, 202b of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 may include a respective groove 209a, 209b, 219a, 219b defined by an outer surface 240 of the refractory tube 200. In some embodiments, each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may be seated within the respective groove 209a, 209b, 219a, 219b of the refractory tube 200.

[00116] Additionally, in some embodiments, each heating element 210a,

210b, 220a, 220b of the plurality of heating elements may be electrically isolated from other heating elements of the plurality of heating elements. Electrically isolating each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may prevent arcing of an electric current between each heating element 210a, 210b, 220a, 220b of the plurality of heating elements. In some embodiments, the outer surface 240 of the refractory tube 200 may include a channel portion that may electrically isolate each heating element 210a, 210b, 220a, 220b of the plurality of heating elements. In some embodiments, each circumferential portion 201a, 201b, 202a, 202b of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 may be spaced apart from each other with a respective channel portion 601, 602 of the refractory tube 200 (shown in FIG. 6) and a respective channel portion 701, 702 of the refractory tube 200 (shown in FIG. 7) extending along the axis 280 of the refractory tube 200 and radially positioned between each circumferential portion 201a, 201b, 202a, 202b. In some embodiments, the respective channel portions 601, 602, 701, 702 of the refractory tube 200 may electrically isolate each heating element 210a, 210b, 220a, 220b of the plurality of heating elements.

[00117] For example, in some embodiments, electrically isolating each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may include positioning each heating element 210a, 210b, 220a, 220b of the plurality of heating elements a predetermined distance away from the other heating elements of the plurality of heating elements where the distance is selected such that an electric current cannot arc between each heating element 210a, 210b, 220a, 220b of the plurality of heating elements across the distance. For example, in some embodiments, at least a portion of the channel portions 601, 602, 701, 702 of the refractory tube 200 may define the predetermined distance between one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements. In some embodiments, electrically isolating each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may include providing an electrically non-conductive material between each heating element 210a, 210b, 220a, 220b of the plurality of heating elements that prevents arcing of electric current between each heating element 210a, 210b, 220a, 220b of the plurality of heating elements. Accordingly, in some embodiments, each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may be independently operated to selectively heat the respective circumferential portion 201a, 201b of the first length 201 and the respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200.

[00118] Conversely, for example, if one or more heating elements 210a,

210b, 220a, 220b of the plurality of heating elements was not electrically isolated from one or more other heating elements of the plurality of heating elements, in some embodiments, arcing of an electric current between the one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements and the one or more other heating elements of the plurality of heating elements could occur. Electric arcing between one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements and one or more other heating elements of the plurality of heating elements may interfere with independent operation of each heating element 210a, 210b, 220a, 220b of the plurality of heating elements thereby prohibiting selective heating of a respective circumferential portion of a respective length of the refractory tube 200.

[00119] In some embodiments, electrically isolating each heating element 210a, 210b, 220a, 220b of the plurality of heating elements from other heating elements of the plurality of heating elements may provide refined, independent temperature control of two or more circumferential portions of lengths of the refractory tube 200 as compared to heating the refractory tube 200 with a single heating element or with multiple heating elements that are not electrically isolated from each other. That is, heating the refractory tube 200 with a single heating element or with multiple heating elements that are not electrically isolated from each other may provide less refined temperature control where only a single circumferential portion of a length of the refractory tube 200 or only the entire refractory tube 200, for example, may be heated.

[00120] Accordingly, in some embodiments, each heating element 210a,

210b of the plurality of first heating elements may uniformly heat the respective circumferential portion 201a, 201b of the first length 201 of the refractory tube 200 and each heating element 220a, 220b of the plurality of second heating elements may uniformly heat the respective circumferential portion 202a, 202b of the second length 202 of the refractory tube 200. For example, collinearly aligning the axis 280 of the refractory tube 200 and the flow axis 180 of the delivery pipe 139 with each heating element 210a, 210b, 220a, 220b of the plurality of heating elements concentrically aligned along the axis 280 of the refractory tube 200 may provide uniform heating of the molten material 121 within the delivery pipe 139 flowing along the flow axis 180 of the delivery pipe 139. Moreover, in some embodiments, providing independent control of each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may provide independent heating of each heating element 210a, 210b, 220a, 220b of the plurality of heating elements to, for example, compensate for at least one of misalignment of one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements relative to the axis 280 of the refractory tube 200 and misalignment of one or more heating elements 210a, 210b, 220a, 220b of the plurality of heating elements relative to the flow axis 180 of the delivery pipe 139. When employed together to compensate for misalignment, independent heating of each heating element 210a, 210b, 220a, 220b of the plurality of heating elements may provide uniform heating of the molten material 121 within the delivery pipe 139 flowing along the flow axis 180 of the delivery pipe 139.

[00121] Although described with respect to heating elements 210a, 210b that heat corresponding circumferential portions 201a, 201b of the first length 201 of the refractory tube 200 and a heating elements 220a, 220b that heat corresponding circumferential portions 202a, 202b of the second length 202 of the refractory tube 200, it is to be understood that, unless otherwise noted, features of the disclosure may apply to a plurality of heating elements to heat a plurality of circumferential portions of the refractory tube 200. For example, in some embodiments two circumferential portions, each of which circumscribes an approximately 180-degree radial portion of the refractory tube 200, may be provided. In some embodiments, any number of circumferential portions, each of which circumscribes a respective radial portion of the refractory tube 200 may be provided. Moreover, in some embodiments, each circumferential portion may circumscribe a non-equally divided radial portion of the refractory tube 200 relative to the circumference of the refractory tube 200.

[00122] Additionally, in some embodiments, a free end of each heating element of the plurality of heating elements may extend within a respective channel portion 601, 602, 701, 702 of the refractory tube 200. For example, as shown in FIG. 6, free end 211a of heating element 210a and free end 211b of heating element 210b may extend in channel portion 601 of the first length 201 of the refractory tube 200. By extending in the channel portion 601, the free ends 211a, 211b of the respective heating elements 210a, 210b may extend together and be positioned in a location spaced from the refractory tube 200 to enable, for example, connection of the free ends 211a, 211b to the respective first power sources 401a, 401b. As shown in FIG. 7, in some embodiments, heating element 210a and heating element 210b may extend in channel portion 701 of the first length 201 of the refractory tube 200 to wind back and forth within the respective grooves 209a, 209b of the first length 201 of the refractory tube 200 relative to the axis 280 of the refractory tube 200 on the respective circumferential portions 201a, 201b of the first length 201 of the refractory tube 200. Accordingly, by winding the heating elements 210a, 210b back and forth, the free ends 211a, 221b of the heating elements 210a, 210b may loop back to a common location of the refractory tube 200 (e.g., channel portion 601, shown in FIG. 6).

[00123] Similarly, as shown in FIG. 7, free end 221a of heating element

220a and free end 221b of heating element 220b may extend in channel portion 702 of the second length 202 of the refractory tube 200. By extending in the channel portion 702, the free ends 221a, 221b of the respective heating elements 220a, 220b may extend together and be positioned in a location spaced from the refractory tube 200 to enable, for example, connection of the free ends 221a, 221b to the respective second power sources 402a, 402b. In some embodiments, heating element 220a and heating element 220b may extend in channel portion 602 of the second length 202 of the refractory tube 200 to wind back and forth within the respective grooves 219a, 219b of the second length 202 of the refractory tube 200 relative to the axis 280 of the refractory tube 200 on the respective circumferential portions 202a, 202b of the second length 202 of the refractory tube 200. Accordingly, by winding the heating elements 220a, 220b back and forth the respective grooves 219a, 219b and the channel portion 602, the free ends 221a, 221b of the heating elements 220a, 220b may loop back to a common location of the refractory tube 200 (e.g., channel portion 702, shown in FIG. 7).

[00124] In some embodiments, the first length 201 of the refractory tube

200 may be axially spaced apart from the second length 202 of the refractory tube 200 along the axis 280 of the refractory tube 200 with the intermediate portion 215 of the refractory tube 200 axially positioned between the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. In some embodiments, at least one of the respective channel portions 601, 602, 701, 702 of the refractory tube 200 may extend along the axis 280 of the refractory tube 200 across the intermediate portion 215 between the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200. For example, as shown in FIG. 7, in some embodiments, free ends 221a, 221b of respective heating elements 220a, 220b of the plurality of second heating elements may extend within the channel portion 702 of the second length 202 of the refractory tube 200 across the intermediate portion 215 between the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 and within channel portion 701 of the first length 201 of the refractory tube 200. By extending within the channel portion 702 of the second length 202 of the refractory tube 200 into channel portion 701 of the first length 201 of the refractory tube 200, in some embodiments, the free ends 221a, 221b of the heating elements 220a, 220b may be positioned in a more accessible location to, for example, connect the free ends 221a, 221b to the second power sources 402a, 402b. That is, for example, if the free ends 221a, 221b of the heating elements 220a, 220b were to terminate at a location within the second length 202 of the refractory tube 200, and therefore not extend into the first length 201 of the refractory tube 200, it may be difficult to connect the free ends 221a, 221b of the heating elements 220a, 220b to the second power sources 402a, 402b when, for example, the refractory tube 200 is positioned in or near the inlet 141 of the glass former 140, as shown in FIG. 2.

[00125] In some embodiments, the glass manufacturing apparatus 101 may include a thermocouple 500 positioned within at least one of the respective channel portions (e.g., channel portion 702) of the refractory tube 200. In some embodiments, a portion of the thermocouple 500 may extend from the outer surface 240 of the refractory tube 200 through a wall of the refractory tube 200 to the inner surface 204 (shown in FIG. 2 and 3) of the refractory tube 200. Accordingly, in some embodiments, the thermocouple 500 may measure a temperature of or corresponding to the molten material 121 within the delivery pipe 139. In some embodiments, the thermocouple lead 501 of the thermocouple 500 may extend within the channel portion 702 of the second length

202 of the refractory tube 200 across the intermediate portion 215 between the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 and within channel portion 701 of the first length 201 of the refractory tube 200. By extending within the channel portion 702 of the second length 202 of the refractory tube

200 into channel portion 701 of the first length 201 of the refractory tube 200, in some embodiments, the thermocouple lead 501 may be positioned in a more accessible location to, for example, connect the thermocouple lead 501 to a controller (not shown). That is, for example, if the thermocouple lead 501 was to terminate at a location within the second length 202 of the refractory tube 200, and therefore not extend into the first length

201 of the refractory tube 200, it may be difficult to connect the thermocouple lead 501 to the controller when the refractory tube 200 is, for example, positioned in or near the inlet 141 of the glass former 140, as shown in FIG. 2.

[00126] Turning back to FIG. 2, in some embodiments, the glass manufacturing apparatus 101 may include a sleeve 275 circumscribing the delivery pipe 139. The sleeve 275 may enclose the refractory tube 200 and, in some embodiments prevent particulates and condensation that may form on the outer surface 240 of the refractory tube 200 from falling into the inlet 141 of the glass former 140 and contaminating molten material 121 in the glass former 140. For example, in some embodiments, an inner surface 274 of the sleeve 275 may be spaced a distance 270 from the outer surface 176 of the delivery pipe 139 thereby defining a space 271 within which the refractory tube 200 may be positioned. In some embodiments, the sleeve 275 may include a flange 276 that abuts the outer surface 176 of the delivery pipe 139 thereby enclosing an end of the space 271. As shown, the flange 276 may include a circumferential flange 276 that extends from a lower end of the sleeve 275 in a direction toward the outer surface 176 of the delivery pipe 139. Consequently, an inner surface of the circumferential flange 276 may act as a trap for debris and condensation thereby preventing particulates and condensation that may form on the outer surface 240 of the refractory tube 200 from falling to the free surface 122 of the molten material 121 within the inlet 141 of the forming vessel 143 positioned below the refractory tube 200.

[00127] In some embodiments, the first heating element 210, the second heating element 220, one or more of the heating elements 210a, 210b of the plurality of first heating elements, and one or more of the heating elements 220a, 220b of the plurality of second heating elements may include a plurality of heating elements electrically connected to each other. That is, the term "heating element" as used throughout the disclosure to refer to the first heating element 210, the second heating element 220, one or more of the heating elements 210a, 210b of the plurality of first heating elements, and one or more of the heating elements 220a, 220b of the plurality of second heating elements should not, unless otherwise noted, be construed as limiting either of the first heating element 210, the second heating element 220, one or more of the heating elements 210a, 210b of the plurality of first heating elements, and one or more of the heating elements 220a, 220b of the plurality of second heating elements to include only a single, physical heating element.

[00128] Moreover, it is to be understood that, in some embodiments, the refractory tube 200 may include a plurality of heating elements (e.g., two, three, four, etc.) and each heating element of the plurality of heating elements may be operable to heat a respective length of a corresponding plurality of lengths of the refractory tube 200 without departing from the scope of the disclosure. Similarly, it is to be understood that, in some embodiments, the refractory tube 200 may include a plurality of heating elements (e.g., two, three, four, etc.) and each heating element of the plurality of heating elements may be operable to heat a respective circumferential portion of a corresponding circumferential portion of a length of the refractory tube 200 without departing from the scope of the disclosure.

[00129] In some embodiments, each heating element of the plurality of heating elements may be electrically isolated from other heating elements of the plurality of heating elements to prevent arcing of an electric current between heating elements of the plurality of heating elements. Additionally, in some embodiments, each heating element of the plurality of heating elements may be independently operated to selectively heat a respective length of the plurality of lengths of the refractory tube 200 as well as a respective circumferential portion of the plurality of circumferential portions of the refractory tube 200. Therefore, although described with respect to a first heating element 210 and a second heating element 220, it is to be understood that, unless otherwise noted, features of the disclosure may apply to a plurality of heating elements to heat a plurality of lengths of a refractory tube 200 and a plurality of circumferential portions of a refractory tube 200. Likewise, although disclosed with respect to the delivery pipe 139 of the glass manufacturing apparatus 101, it is to be understood that the methods and apparatus of the present disclosure may be employed to control a temperature of molten material 121 at any one or more locations within the glass manufacturing apparatus 101 and the glass manufacturing process.

[00130] Referring to FIGS. 2, 8 and 9, the glass manufacturing apparatus

101 can include the refractory device 198 that can include the internal bore 205. Indeed, as shown, the refractory device 198 can include the refractory tube 200 that can include the internal bore 205. Unless otherwise noted, the features of the glass manufacturing apparatus 101 of FIGS. 8 and 9 can be identical to the features of the glass manufacturing apparatus 101 discussed and illustrated with respect to FIGS. 1-7 above. As such, additional features of possible glass manufacturing apparatus will be discussed with respect to FIG. 8 with the understanding that such features may optionally be provided in any of the embodiments of the disclosure. [00131] As shown in FIG. 8, the delivery pipe 139 can include an upstream segment 801 positioned within the internal bore 205 of the refractory tube 200. Consequently, the refractory device 198 can facilitate temperature control of the molten material 121 traveling through the interior pathway 175 of the upstream segment 801 of the delivery pipe 139. Temperature control can be achieved by various embodiments of the refractory device 198. In some embodiments, the refractory device 198 may optionally include a heating component (e.g., heating elements 210, 220) and/or an optional cooling component (not shown). In further embodiments, the refractory device 198 may include the refractory tube 200 alone or in combination with the sleeve 275 or other features without the heating elements 210, 220. In some embodiments, the length of the upstream segment 801 positioned within the refractory tube 200 can be maximized to help control the temperature characteristics of the molten material along the length of the upstream segment 801.

[00132] The delivery pipe 139 can further include a downstream segment

803 protruding out of the internal bore 205 from a lower end 805 of the refractory device 198. In some embodiments, the downstream segment 803 can include the delivery pipe 139 without a casing to allow optional submersion of the outer end 807 below the free surface 122 of molten material 121 of the forming vessel 143. In some embodiments, the downstream segment 803 can include only the delivery pipe that may be fabricated from platinum, platinum alloy material that can withstand the temperature conditions of molten material and can contact the molten material without contaminating the molten material. As shown, the outer end 807 can include a free end that is not supported downstream from the refractory tube 200 but may be suspended from the refractory tube 200. As such, the refractory device 198, in some embodiments, can provide the delivery pipe 139 with an upper segment 801 that is received within the internal bore 205 of the refractory tube 200 to control temperature along a significant length of the delivery pipe 139 while the downstream segment 803 can extend a sufficient distance from the refractory tube 200 to avoid contact of molten material with the refractory tube 200 by molten material 121 leaving the outlet 182 of the delivery pipe 139. Furthermore, the downstream segment 803 can extend a sufficient distance from the refractory tube 200 to avoid contact of molten material with the refractory tube 200 with the free surface 122 of the molten material 121 and/or being submerged in the molten material of the forming vessel 143. Avoiding contact between the refractory tube 200 and the molten material can avoid contamination of the molten material by the refractory tube 200.

[00133] As further illustrated in FIG. 8, the inlet 141 of the forming vessel

143 can further include an interior passage 809 to receive the molten material 121 from the refractory device 198 and/or receive a portion of the refractory device 198. In some embodiments, the interior passage 809 of the inlet 141 can extend along an axis 811 of the inlet, such as a symmetrical axis of the inlet. As shown, in some embodiments, the axis 811 of the inlet 141 can be collinear with the flow axis 180 of the delivery pipe 139 and/or the axis 280 of the refractory tube 200. The interior passage 809 can include an upper portion 813 and a lower portion 815 disposed below the upper portion 813. Indeed, the lower portion 815 can be positioned downstream from the upper portion 813 in the flow direction 184.

[00134] FIG. 9 illustrates a partial cross-section along line 9-9 of FIG. 8 that illustrates profile shapes and relative cross-sectional areas/footprints taken perpendicular to the axes 180, 811. Indeed, FIG. 9 demonstrates the cross-sectional profile shape of an inner surface 901 of an upper axial length "LI" (see FIG. 8) of the upper portion 813 of the interior passage 809 taken perpendicular to the axis 811 of the inlet 141. FIG. 9 further demonstrates the cross-sectional profile shape of an outer periphery of an outer surface 903 of the lower end 805 of the refractory device 198 taken perpendicular to the flow axis 180 of the delivery pipe 139. FIG. 9 still further demonstrates the cross-sectional profile shape of an inner surface 905 of a lower axial length "L2" of the lower portion 815 of the interior passage 809 taken perpendicular to the axis 811 of the inlet 141. FIG. 9 also demonstrates the cross-sectional profile shape of the outer surface 907 of the outer end 807 of the delivery pipe 139 along the flow axis 180 of the delivery pipe 139.

[00135] FIG. 10 illustrates that, in some embodiments, an upper cross- sectional area 1001 of the upper portion 813 of the interior passage 809 taken perpendicular to the axis 811 of the inlet 141 is larger than a lower cross-sectional area 1003 of the lower portion 815 of the interior passage 809 taken perpendicular to the axis 811 of the inlet 141. Referring to FIG. 11, in some embodiments, the outer periphery 903 of the lower end 805 of the refractory device 198 can define a cross-sectional footprint 1101 taken perpendicular to the axis 180 of the delivery pipe 139. The outer periphery 907 of the free end 807 of the downstream segment 803 of the delivery pipe 139 further defines a cross-sectional footprint 1103 taken perpendicular to the flow axis 180 of the delivery pipe 139. As shown in FIG. 11, the cross-sectional footprint 1101 of the lower end 805 of the refractory device 198 is larger than the cross-sectional footprint 1103 of the free end 807 of the downstream segment 803 of the delivery pipe 139.

[00136] As shown in FIGS. 2, 8 and 12, the forming vessel 143 may include molten material 121 with the free surface 122 positioned within the lower portion 815 of the interior passage 809. Disposing the free surface 122 of the molten material 121 within the lower portion 815 can be desirable in some embodiments to allow a constant change in volume per unit length as the free surface 122 may be raised or lowered in the lower portion 815. Indeed, as shown, the lower cross-sectional area 1003 of the lower portion 815 of the interior passage 809 is substantially constant along an axial length "L2" of the lower portion 815 of the interior passage 809 to allow the above- referenced constant change in volume per unit length.

[00137] As shown in FIGS. 10-11, the cross-sectional footprint 1103 of the free end 807 of the downstream segment 803 of the delivery pipe 139 can be smaller than the lower cross-sectional area 1003 of the lower portion 815 of the interior passage 809. As such, as shown in FIG. 8, the free end 807 of the delivery pipe 139 may be positioned within the lower portion 815 of the interior passage 809 to allow positioning of the free end 807 near the free surface 122 of the molten material 121 to avoid undesirable flow characteristics that might otherwise occur as the molten material 121 passes from the outlet 182 of the delivery pipe to the forming vessel 143.

[00138] Since the cross-sectional footprint 1103 of the free end 807 may be smaller than the lower cross-sectional area 1103 of the lower portion 815 of the interior passage 809, the delivery pipe may reach down to dispose the free end 807 of the delivery pipe within the lower portion 815 of the interior passage near the free surface 122 to provide a desired flow profile as the molten material 121 passes to the forming vessel 143 from the outlet 182 of the delivery pipe 139. As shown in FIG. 2, in some embodiments, the free end 807 may be disposed within the axial length "L2" of the lower portion 815 of the interior passage 809 while being positioned above the free surface 122 of the molten material 121. Alternatively, as shown in FIG. 8, in some embodiments, the free end 807 may be disposed within the axial length "L2" of the lower portion 815 of the interior passage 809 while being positioned below the free surface 122 of the molten material 121. In still further embodiments, the free end 807 of the delivery pipe 139 may be positioned within the upper portion 813 of the interior passage as shown in FIG. 12.

[00139] The lower cross-sectional area 1003 of the lower portion 815 of the interior passage 809 of the inlet 141 may be carefully selected to provide the desired level of pressure at the bottom of the inlet to promote a desired flow rate of molten material being processed into glass ribbon 103 by the forming vessel 143. While the free end 807 of the delivery pipe 139 may be inserted into the lower portion 815 of the interior passage 809, there may be insufficient clearance for the lower end 805 of the refractory device 198 to be received by the lower portion 815 of the interior passage 809. Thus, in some embodiments, although not shown, the refractory device 198 may be shortened such that the lower end 805 of the refractory device 198 is positioned farther away from the free end 807 of the delivery pipe 139 such that the lower portion 815 is not received by the interior passage 809 of the inlet 141. In such embodiments, a relatively longer length of the delivery pipe 139 extends from the lower end 805 of the refractory device 198 without receiving the benefits of thermal control over the relatively longer length of the delivery pipe 139.

[00140] To maintain the desired thermal control over a maximum length of the delivery pipe 139, rather than shortening the refractory device 198, as shown in FIGS. 2, 8 and 12, the upper portion 813 of the inlet can be expanded to a larger cross sectional area than the cross sectional area 1003 of the lower portion 815. For example, as shown in FIGS. 10 and 11, the cross- sectional footprint 1101 of the lower end 805 of the refractory device 198 can be less than the upper cross sectional area 1001 of the upper portion 813 of the interior passage 809 while being greater than the lower cross-sectional area 1003 of the lower portion 815 of the interior passage 809. Thus, as shown, the lower end 805 of the refractory device 198 may be positioned within the upper portion 813 of the interior passage 809 even though the lower end 805 is too large to fit within the lower portion 815 of the interior passage 809.

[00141] To minimize heat loss and cost of materials, the expanded cross sectional area of the upper portion 813 can be limited in size but, at the same time, large enough to avoid inadvertent contact between the inlet 141 and the refractory device 198 that can may otherwise result electrical shorting or damage to the inlet and/or refractory device 198. To avoid inadvertent contact between the refractory device 198 and the inlet 141 during installation, heat up/cool down, relative pivoting between the refractory device 198 and inlet, a minimum distance "D" (see FIG. 8) between the refractory device and an inner surface of the inlet may be greater than or equal to 1.27 cm, for example greater than or equal to 1.5 cm, for example greater than or equal to 2 cm, for example greater than or equal to 2.5 cm, for example greater than or equal to 3 cm. Although "D" can be provided within a wide variety of ranges, in some embodiment, the distance "D" can be within a range of from about 1.27 cm to about 1.5 cm, for example, from about 1.27 cm to about 2 cm, for example, from about 1.27 cm to about 2.5 cm, for example from about 1.27 cm to about 3 cm.

[00142] In some embodiments, although not shown, the inlet 141 can be designed with a step change in cross-section of the interior passage. In alternative embodiments, as shown in FIG. 8, the upper portion 813 may include an upper axial length "LI" and a lower axial length "L3" extending between the upper axial length "LI" and the lower portion 815. As shown, in some embodiments, the lower axial length "L3" may continuously reduce in size along the lower axial length "L3" from the upper axial length "LI" to the lower portion 815 in a downstream direction of the axis 811 of the inlet 141 such as the direction 184. As such, the lower axial length "L3" can include a tapered portion that tapers to the lower portion 815 of the interior passage 809. In some embodiments, as shown, the tapered portion can comprise a firustoconical segment extending between the upper axial length "LI" and the lower portion 815 and tapering in the direction 184. Providing a tapered portion can avoid a horizontal shelf portion that may result in undesired pooling of stagnant molten glass if the free surface 122 inadvertently raises above the lower portion 815. Rather, the tapered configuration would allow the molten material 121 to more easily drain back into the lower portion 815 once the free surface 122 retreats back to the lower portion 815. Furthermore, a tapered lower axial length "L3" can withstand larger axial loads compared to a horizontal segment and can thereby increase the strength of the inlet 141 when compared to embodiments including a horizontal segment.

[00143] In further embodiments, the upper cross-sectional area 1001 the upper axial length "LI" (see FIG. 8) of the upper portion 813 of the interior passage 809 may be substantially constant along the upper axial length "LI". For instance, as shown in FIG. 8, the lower axial length "L3" can be positioned between the upper axial length "LI" and the lower portion 815 of the interior passage 809. Providing an upper axial length "LI" with a substantially constant cross section can reduce the amount of material necessary to produce the inlet while still achieving a desired opening cross section into the interior passage of the inlet. Although not shown, in some embodiments, the upper axial length with substantially constant cross section may not be included, for example, if the desired opening cross section is achieved by the tapered portion.

[00144] As shown in FIG. 8, the inlet 141 of any of the embodiments of the disclosure may be provided with optional heating coils 817 that may add heat to the inlet 141 to further help control the temperature of the molten material 121 existing the outlet 182 of the delivery pipe 139 and/or to help control temperature of the molten material as it travels through the interior passage 809 of the inlet 141.

[00145] In some embodiments, a method of manufacturing glass may include flowing molten material 121 through the interior pathway 175 defined by the delivery pipe 139 along the flow direction 184 of the flow axis 180 of the delivery pipe 139. As shown in FIG. 2, the delivery pipe 139 may be positioned in the internal bore 205 of the refractory tube 200. The method may include heating the molten material 121 within the delivery pipe 139 by heating the first length 201 of the refractory tube 200 with the first heating element 210 and heating the second length 202 of the refractory tube 200 with the second heating element 220 that may be electrically isolated from the first heating element 210. In some embodiments, heating the molten material 121 within the delivery pipe 139 may include heating a respective circumferential portion (e.g., one or more circumferential portions 201a, 201b, 202a, 202b, shown in FIGS. 6 and 7) of a corresponding plurality of circumferential portions of a respective one of at least one of the first length 201 of the refractory tube 200 and the second length 202 of the refractory tube 200 with at least one of a corresponding plurality of first heating elements (e.g., heating elements 210a, 210b) and a corresponding plurality of second heating elements (e.g., heating elements 220a, 220b). In some embodiments, each heating element of the corresponding plurality of first heating elements (e.g., heating elements 210a, 210b) and each heating element of the corresponding plurality of second heating elements (e.g., heating elements 220a, 220b) may be electrically isolated from other heating elements of the corresponding plurality of first heating elements and the corresponding plurality of second heating elements.

[00146] Additionally, in some embodiments, the method may include measuring a temperature of the molten material 121 within the delivery pipe 139, for example with thermocouple 500 (shown in FIG. 7), and then operating at least one of the first heating element 210 and the second heating element 220 based on the measured temperature. Moreover, in some embodiments, the glass manufacturing apparatus 101 may operate to provide a glass manufacturing process that may include providing the heated molten material 121 from the delivery pipe 139 to the inlet 141 of the forming vessel 143 of the glass former 140 and then forming a glass ribbon 103 from the molten material 121 with the glass former 140.

[00147] Methods of manufacturing glass may be further conducted with, as shown in FIG. 8, the delivery pipe 139 comprising the upstream segment 801 positioned within the internal bore 205 of the refractory device 198 and the downstream segment 803 protruding out of the internal bore 205 from the lower end 805 of the refractory device 198. As shown in FIG. 8, the lower end 805 of the refractory device 198 is positioned within the interior passage 809 of the inlet 141 of the forming vessel 143. As such, thermal control of the molten material traveling within the delivery pipe 139 may be conducted throughout a longer length of the delivery pipe 139 since the lower end 805 of the refractory device 198 may be received within the upper portion 813 of the interior passage 809 of the inlet 141. The method can further include flowing molten material 121 through the outlet 182 of the downstream segment 803 of the delivery pipe 139 positioned within the interior passage 809 of the inlet 141 of the forming vessel 143 to provide the forming vessel 143 with the free surface 122 of the molten material 121 positioned within the interior passage 809 of the inlet 141. Turning to FIG. 1, the method can further include forming the glass ribbon 103 from the molten material with the forming vessel 143.

[0001] It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

[0002] It is to be understood that, as used throughout the disclosure, the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0003] Ranges may be expressed throughout the disclosure as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, embodiments 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.

[0004] Unless otherwise expressly stated, it is in no way intended that any method set forth in the disclosure may 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 no way intended that any particular order be inferred.

[0005] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase "comprising," it is to be understood that alternative embodiments, including those that may be described using the transitional phrases "consisting" or "consisting essentially of," are implied. Thus, for example, implied alternative embodiments to an apparatus that comprises A+B+C include embodiments where an apparatus consists of A+B+C and embodiments where an apparatus consists essentially of A+B+C.

[0006] It will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. A glass manufacturing apparatus comprising:

a refractory tube comprising a first heating element operable to heat a first length of the refractory tube and a second heating element operable to heat a second length of the refractory tube, wherein the first heating element is electrically isolated from the second heating element; and

a conduit positioned in an internal bore of the refractory tube, wherein an outer surface of the conduit faces an inner surface of the internal bore along the first length and the second length, and wherein an inner surface of the conduit defines an interior pathway extending along a flow axis of the conduit.

2. The glass manufacturing apparatus of claim 1, further comprising a glass former to form a glass ribbon, the glass former comprising a forming vessel and the conduit comprising a delivery pipe, wherein an outlet of the delivery pipe extends into an inlet of the forming vessel.

3. The glass manufacturing apparatus of claim 2, wherein the delivery pipe comprises an upstream segment positioned within the internal bore of the refractory tube, and a downstream segment protruding out of the internal bore from a lower end of the refractory tube.

4. The glass manufacturing apparatus of claim 3, wherein the inlet of the forming vessel comprises an interior passage extending along an axis of the inlet, the interior passage comprising an upper portion and a lower portion, wherein an upper cross-sectional area of the upper portion of the interior passage taken perpendicular to the axis of the inlet is larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis of the inlet, and the lower end of the refractory tube is positioned within the upper portion of the interior passage.

5. The glass manufacturing apparatus of claim 4, wherein the downstream segment of the delivery pipe comprises a free end including the outlet of the delivery pipe.

6. The glass manufacturing apparatus of claim 5, wherein the free end of the delivery pipe is positioned within the lower portion of the interior passage.

7. The glass manufacturing apparatus of claim 4, wherein the forming vessel comprises molten material with a free surface positioned within the lower portion of the interior passage.

8. The glass manufacturing apparatus of claim 7, wherein the free end of the delivery pipe is positioned above the free surface of the molten material.

9. The glass manufacturing apparatus of claim 7, wherein the free end of the delivery pipe is positioned below the free surface of the molten material.

10 The glass manufacturing apparatus of claim 4, wherein the lower cross-sectional area is substantially constant along an axial length of the lower portion of the interior passage.

11. The glass manufacturing apparatus of claim 10, wherein the downstream segment of the delivery pipe comprises a free end positioned within the axial length of the lower portion of the interior passage.

12. The glass manufacturing apparatus of claim 4, wherein the lower end of the refractory tube comprises an outer periphery defining a cross-sectional footprint taken perpendicular to the flow axis, wherein the cross-sectional footprint of the lower end of the refractory tube is greater than the lower cross-sectional area of the lower portion of the interior passage.

13. The glass manufacturing apparatus of claim 12, wherein the downstream segment of the delivery pipe comprises a free end comprising an outer periphery defining a cross- sectional footprint taken perpendicular to the flow axis, wherein the cross-sectional footprint of the free end of the delivery pipe is smaller than the lower cross-sectional area of the lower portion of the interior passage.

14. The glass manufacturing apparatus of claim 4, wherein a minimum distance between the refractory tube and an inner surface of the inlet is greater than or equal to 1.27 cm.

15. The glass manufacturing apparatus of claim 4, wherein the upper portion of the interior passage comprises an upper axial length along the axis of the inlet, wherein the upper cross-sectional area of the upper portion is substantially constant along the upper axial length.

16. The glass manufacturing apparatus of claim 4, wherein the upper portion of the interior passage comprises a lower axial length, wherein the upper cross-sectional area of the upper portion continuously reduces in size along the lower axial length in a downstream direction of the axis of the inlet.

17. The glass manufacturing apparatus of claim 16, wherein the upper portion of the interior passage further comprises an upper axial length along the axis of the inlet, wherein the upper cross-sectional area of the upper portion is substantially constant along the upper axial length, and the lower axial length is positioned between the upper axial length and the lower portion of the interior passage.

18. The glass manufacturing apparatus of claim 1, wherein the inner surface of the internal bore of the refractory tube circumscribes the outer surface of the conduit along the flow axis.

19. The glass manufacturing apparatus of claim 1, wherein the first length of the refractory tube is axially spaced apart from the second length of the refractory tube along an axis of the refractory tube with an intermediate portion of the refractory tube axially positioned between the first length of the refractory tube and the second length of the refractory tube.

20. The glass manufacturing apparatus of claim 19, wherein the intermediate portion of the refractory tube electrically isolates the first heating element from the second heating element.

21. The glass manufacturing apparatus of claim 1, wherein the first heating element is mounted to the first length of the refractory tube and the second heating element is mounted to the second length of the refractory tube.

22. The glass manufacturing apparatus of claim 1, wherein the inner surface of the conduit has a circular cross-sectional profile taken perpendicular to the flow axis of the conduit.

23. The glass manufacturing apparatus of claim 1, wherein a free end of the first heating element extends from a first side of the refractory tube, and a free end of the second heating element extends from a second side of the refractory tube, and wherein the first side is opposite the second side.

24. The glass manufacturing apparatus of claim 1, wherein the first heating element and the second heating element are concentrically aligned along an axis of the refractory tube.

25. The glass manufacturing apparatus of claim 24, wherein the axis of the refractory tube and the flow axis of the conduit are collinear.

26. The glass manufacturing apparatus of claim 1, wherein the first heating element is wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element is wound about the axis of the refractory tube along the second length of the refractory tube.

27. The glass manufacturing apparatus of claim 26, wherein at least one of the first heating element and the second heating element is helically wound about the axis of the refractory tube.

28. The glass manufacturing apparatus of claim 26, wherein the first heating element is seated within a first groove defined by an outer surface of the refractory tube, and the second heating element is seated within a second groove defined by the outer surface of the refractory tube.

29. The glass manufacturing apparatus of claim 28, wherein the first groove and the second groove are concentrically aligned along the axis of the refractory tube.

30. The glass manufacturing apparatus of claim 28, wherein the first groove is spaced apart from the second groove along the axis of the refractory tube with an intermediate portion of the refractory tube axially positioned between the first groove and the second groove, wherein the intermediate portion of the refractory tube electrically isolates the first heating element from the second heating element.

31. The glass manufacturing apparatus of claim 28, comprising a layer of cement covering at least a portion of the outer surface of the refractory tube, wherein the layer of cement at least partially encapsulates the first heating element within the first groove and at least partially encapsulates the second heating element within the second groove.

32. The glass manufacturing apparatus of claim 1, wherein at least one of the first heating element and the second heating element comprises a plurality of heating elements, wherein each heating element of the plurality of heating elements is operable to heat a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube, and wherein each heating element of the plurality of heating elements is electrically isolated from other heating elements of the plurality of heating elements.

33. The glass manufacturing apparatus of claim 32, wherein each heating element of the plurality of heating elements is mounted to the respective circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube.

34. The glass manufacturing apparatus of claim 33, wherein the respective

circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube comprises a respective groove defined by an outer surface of the refractory tube, and wherein each heating element of the plurality of heating elements is seated within the respective groove.

35. The glass manufacturing apparatus of claim 32, wherein each circumferential portion of the corresponding plurality of circumferential portions of the respective one of the at least one of the first length of the refractory tube and the second length of the refractory tube is spaced apart from other circumferential portions of the corresponding plurality of circumferential portions with a respective channel portion of the refractory tube extending along an axis of the refractory tube and radially positioned between each circumferential portion.

36. The glass manufacturing apparatus of claim 35, wherein the respective channel portion of the refractory tube electrically isolates each heating element of the plurality of heating elements.

37. The glass manufacturing apparatus of claim 35, wherein a free end of each heating element of the plurality of heating elements extends within the respective channel portion of the refractory tube.

38. The glass manufacturing apparatus of claim 35, wherein the first length of the refractory tube is axially spaced apart from the second length of the refractory tube along the flow axis with an intermediate portion of the refractory tube axially positioned between the first length of the refractory tube and the second length of the refractory tube, and wherein at least one of the respective channel portions of the refractory tube extends along the axis of the refractory tube across the intermediate portion between the first length of the refractory tube and the second length of the refractory tube.

39. The glass manufacturing apparatus of claim 38, wherein a free end of at least one heating element of the plurality of heating elements of the second heating element extends within the at least one of the respective channel portions of the refractory tube across the intermediate portion between the first length of the refractory tube and the second length of the refractory tube.

40. The glass manufacturing apparatus of claim 35, further comprising a thermocouple positioned within at least one of the respective channel portions of the refractory tube.

41. The glass manufacturing apparatus of claim 40, wherein a portion of the

thermocouple extends from an outer surface of the refractory tube to the inner surface of the refractory tube.

42. The glass manufacturing apparatus of claim 1, further comprising a sleeve circumscribing the conduit, wherein an inner surface of the sleeve is spaced a distance from the outer surface of the conduit thereby defining a space within which the refractory tube is positioned, and wherein the sleeve comprises a flange that abuts the outer surface of the conduit thereby enclosing an end of the space.

43. A glass manufacturing apparatus comprising:

a refractory device comprising an internal bore;

a delivery pipe comprising an upstream segment positioned within the internal bore and a downstream segment protruding out of the internal bore from a lower end of the refractory device; and

a forming vessel comprising an inlet comprising an interior passage extending along an axis of the inlet, the interior passage comprising an upper portion and a lower portion, wherein an upper cross-sectional area of the upper portion of the interior passage taken perpendicular to the axis is larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis, and the lower end of the refractory device is positioned within the upper portion of the interior passage.

44. The glass manufacturing apparatus of claim 43, wherein the downstream segment of the delivery pipe comprises a free end.

45. The glass manufacturing apparatus of claim 44, wherein the free end of the delivery pipe is positioned within the lower portion of the interior passage.

46. The glass manufacturing apparatus of claim 44, wherein the forming vessel comprises molten material with a free surface positioned within the lower portion of the interior passage.

47. The glass manufacturing apparatus of claim 46, wherein the free end of the delivery pipe is positioned above the free surface of the molten material.

48. The glass manufacturing apparatus of claim 46, wherein the free end of the delivery pipe is positioned below the free surface of the molten material.

49. The glass manufacturing apparatus of claim 43, wherein the lower cross-sectional area is substantially constant along an axial length of the lower portion of the interior passage.

50 The glass manufacturing apparatus of claim 49, wherein the downstream segment of the delivery pipe comprises a free end positioned within the axial length of the lower portion of the interior passage.

51. The glass manufacturing apparatus of claim 43, wherein the lower end of the refractory device comprises an outer periphery defining a cross-sectional footprint taken perpendicular to an axis of the delivery pipe, wherein the cross-sectional footprint of the lower end of the refractory device is greater than the lower cross-sectional area of the lower portion of the interior passage.

52. The glass manufacturing apparatus of claim 51, wherein the downstream segment of the delivery pipe comprises a free end comprising an outer periphery defining a cross- sectional footprint taken perpendicular to the axis of the delivery pipe, wherein the cross- sectional footprint of the free end of the delivery pipe is smaller than the lower cross- sectional area of the lower portion of the interior passage.

53. The glass manufacturing apparatus of claim 43, wherein a minimum distance between the refractory device and an inner surface of the inlet is greater than or equal to 1.27 cm.

54. The glass manufacturing apparatus of claim 43, wherein the upper portion of the interior passage comprises an upper axial length along the axis of the inlet, wherein the upper cross-sectional area of the upper portion is substantially constant along the upper axial length.

55. The glass manufacturing apparatus of claim 43, wherein the upper portion of the interior passage comprises a lower axial length, wherein the upper cross-sectional area of the upper portion continuously reduces in size along the lower axial length in a downstream direction of the axis of the inlet.

56. The glass manufacturing apparatus of claim 55, wherein the upper portion of the interior passage further comprises an upper axial length along the axis of the inlet, wherein the upper cross-sectional area of the upper portion is substantially constant along the upper axial length, and the lower axial length is positioned between the upper axial length and the lower portion of the interior passage.

57. A method of manufacturing glass comprising:

flowing molten material through an interior pathway defined by a conduit along a flow axis of the conduit, wherein the conduit is positioned in an internal bore of a refractory tube; and

heating the molten material within the conduit by heating a first length of the refractory tube with a first heating element and heating a second length of the refractory tube with a second heating element that is electrically isolated from the first heating element.

58. The method of claim 57, wherein heating the molten material within the conduit comprises heating a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube with at least one of a corresponding plurality of first heating elements and a corresponding plurality of second heating elements.

59. The method of claim 58, wherein each heating element of the corresponding plurality of first heating elements and each heating element of the corresponding plurality of second heating elements is electrically isolated from other heating elements of the corresponding plurality of first heating elements and the corresponding plurality of second heating elements.

60. The method of claim 57, further comprising measuring a temperature of the molten material within the conduit, and then operating at least one of the first heating element and the second heating element based on the measured temperature.

61. The method of claim 57, wherein the first heating element is wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element is wound about the axis of the refractory tube along the second length of the refractory tube.

62. The method of claim 61, wherein at least one of the first heating element and the second heating element is helically wound about the axis of the refractory tube.

63. The method of claim 57, wherein the flow axis of the conduit extends in the direction of gravity, and wherein the flow axis of the conduit and an axis of the refractory tube are collinear.

64. The method of claim 57, wherein the conduit comprises a delivery pipe, the method further comprising providing the heated molten material from the delivery pipe to an inlet of a forming vessel of a glass former and then forming a glass ribbon from the molten material with the glass former.

65. The method of claim 64, wherein the inlet of the forming vessel comprises an interior passage extending along an axis of the inlet, the interior passage comprising an upper portion and a lower portion, wherein an upper cross-sectional area of the upper portion of the interior passage taken perpendicular to the axis is larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis, a lower end of the refractory tube is positioned within the upper portion of the interior passage, and a free surface of molten material of the glass former is positioned within the lower portion of the interior passage.

66. The method of claim 65, wherein the downstream segment of the delivery pipe comprises a free end.

67. The method of claim 66, wherein the free end of the delivery pipe is positioned within the lower portion of the interior passage.

68. The method of claim 66, wherein the free end of the delivery pipe is positioned above the free surface of the molten material.

69. The method of claim 66, wherein the free end of the delivery pipe is positioned below the free surface of the molten material.

70. The method of claim 64, wherein a minimum distance between the refractory tube and an inner surface of the inlet is greater than or equal to 1.27 cm.

71. A method of manufacturing glass with a delivery pipe comprising an upstream segment positioned within an internal bore of a refractory device and a downstream segment protruding out of the internal bore from a lower end of the refractory device, wherein the lower end of the refractory device is positioned within an interior passage of an inlet of a forming vessel, the method comprising:

flowing molten material through an outlet of the downstream segment of the delivery pipe positioned within the interior passage of the inlet of the forming vessel to provide the forming vessel with a free surface of the molten material positioned within the interior passage of the inlet; and forming a glass ribbon from the molten material with the forming vessel.

72. The method of claim 71, further comprising heating the molten material within the delivery pipe by heating a first length of a refractory tube of the refractory device with a first heating element and heating a second length of the refractory tube with a second heating element that is electrically isolated from the first heating element.

73. The method of claim 72, wherein heating the molten material within the delivery pipe comprises heating a respective circumferential portion of a corresponding plurality of circumferential portions of a respective one of at least one of the first length of the refractory tube and the second length of the refractory tube with at least one of a corresponding plurality of first heating elements and a corresponding plurality of second heating elements.

74. The method of claim 73, wherein each heating element of the corresponding plurality of first heating elements and each heating element of the corresponding plurality of second heating elements is electrically isolated from other heating elements of the corresponding plurality of first heating elements and the corresponding plurality of second heating elements.

75. The method of claim 72, further comprising measuring a temperature of the molten material within the delivery pipe, and then operating at least one of the first heating element and the second heating element based on the measured temperature.

76. The method of claim 72, wherein the first heating element is wound about an axis of the refractory tube along the first length of the refractory tube, and the second heating element is wound about the axis of the refractory tube along the second length of the refractory tube.

77. The method of claim 76, wherein at least one of the first heating element and the second heating element is helically wound about the axis of the refractory tube.

78. The method of claim 71, wherein the molten material flows along a flow axis of the delivery pipe to the outlet of the downstream segment, the flow axis extending in the direction of gravity, and the flow axis is collinear with an axis of a refractory tube of the refractory device.

79. The method of claim 71, wherein the interior passage of the inlet extends along an axis of the inlet and the inlet comprises an upper portion and a lower portion, wherein an upper cross-sectional area of the upper portion of the interior passage taken perpendicular to the axis is larger than a lower cross-sectional area of the lower portion of the interior passage taken perpendicular to the axis, and the lower end of the refractory device is positioned within the upper portion of the interior passage, and the free surface of molten material is positioned within the lower portion of the interior passage.

80. The method of claim 79, wherein the downstream segment of the delivery pipe comprises a free end including the outlet.

81. The method of claim 80, wherein the free end of the delivery pipe is positioned within the lower portion of the interior passage.

82. The method of claim 80, wherein the free end of the delivery pipe is positioned above the free surface of the molten material.

83. The method of claim 80, wherein the free end of the delivery pipe is positioned below the free surface of the molten material.

84. The method of claim 71, wherein a minimum distance between the refractory device and an inner surface of the inlet is greater than or equal to 1.27 cm.