WO2017079390A1

WO2017079390A1 - Determining electrode length in a melting furnace

Info

Publication number: WO2017079390A1
Application number: PCT/US2016/060255
Authority: WO
Inventors: Raymond Eugene Fraley; William Brashear Mattingly Iii; Sergey Y POTAPENKO
Original assignee: Corning Incorporated
Priority date: 2015-11-05
Filing date: 2016-11-03
Publication date: 2017-05-11
Also published as: CN108291779A; KR20180066261A; TW201722199A; JP2019504286A

Abstract

A method of indicating a length of an electrode for an apparatus that melts batch materials is provided. The method includes providing a first signal indicative of temperature at a first temperature measurement point positioned along the electrode using a first temperature sensor. A second signal indicative of temperature is provided at a second temperature measurement point positioned along the electrode using a second temperature sensor. An electrode length is determined to a hot face of the electrode based on the first and second signals.

Description

DETERMINING ELECTRODE LENGTH IN A MELTING FURNACE

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/251223 filed on November 5, 2015, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND FIELD

[0002] The present disclosure relates to methods and apparatuses for melting batch materials, and more particularly to methods and apparatus for melting batch materials and use of temperature information within an electrode to determine electrode length in such apparatuses.

Technical Background

[0003] Melting furnaces can be used to melt a wide variety of batch materials, such as glass and metal batch materials, to name a few. Batch materials can be placed in a vessel having two or more electrodes and melted by applying voltage across the electrodes to drive current through the batch, thereby heating and melting the batch. The life cycle of a melting furnace can depend, on electrode wear. For instance, during the melting process, the electrode can be gradually worn down due to contact with the molten batch materials. At some point, the electrode may become too short and may compromise the safe operation of the furnace. For instance, if the electrode wears down past a predetermined point during operation, the batch materials may come into contact with furnace components that may contaminate the batch. In the case of a glass melt, for example, such contact may introduce unwanted contaminants and/or color into the glass melt or final glass product. Moreover, any holes in the electrode and/or furnace can also provide a pathway for leakage of the batch materials, which could compromise the operational safety of the furnace.

[0004] Accurately predicting the end-of-life point for a melting furnace can yield significant cost savings (by avoiding premature shutdown of the furnace) while also maintaining operational safety. However, during a melting operation, it may not be possible to directly observe or measure the electrode length within the vessel. In addition, during operation, several variables can affect the electrode wear rate, such as batch material composition and/or operating temperature, which may complicate the prediction of electrode wear or make a correct prediction unlikely.

[0005] Accordingly, it would be advantageous to provide methods for accurately estimating the length of electrodes in melting furnaces, which can lead to longer operating times and lower operational costs for melting furnaces. Moreover, it would be advantageous to provide apparatuses for melting batch materials that can use temperature information within an electrode as indicative of electrode length.

SUMMARY

[0006] According to one embodiment, a method of indicating a length of an electrode for an apparatus that melts batch materials is provided. The method includes providing a first signal indicative of temperature at a first temperature measurement point positioned along the electrode using a first temperature sensor. A second signal indicative of temperature is provided at a second temperature measurement point positioned along the electrode using a second temperature sensor. An electrode length is determined to a hot face of the electrode based on the first and second signals.

[0007] In another embodiment, an apparatus for melting batch materials includes a vessel and an electrode located in the vessel having an electrode length measured along an axis between a hot face and cold face of the electrode. A thermal length measurement assembly includes a first temperature sensor arranged and configured to provide a first signal indicative of a temperature at a first temperature measurement point positioned along the electrode. A second temperature sensor is arranged and configured to provide a second signal indicative of a temperature at a second temperature measurement point positioned along the electrode. The first and second signals used to determine the electrode length. [0008] In another embodiment, a thermal length measurement assembly for an apparatus for melting batch materials includes a temperature sensor arranged and configured to provide a signal indicative of a temperature at a temperature measurement point positioned along a electrode. A measurement module includes a processor that receives the signal indicative of temperature at the temperature measurement point. The measurement module includes logic executable by the processor that determines an electrode length to a hot face of the electrode based on the signal indicative of temperature.

[0009] Additional features and advantages described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0010] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] These and other features, aspects and advantages of the present disclosure are better understood when the following detailed description of the disclosure is read with reference to the accompanying drawings, in which:

[0012] FIG. 1 is a schematic diagram illustrating a vertical cross-sectional view of an embodiment of a melting furnace (also referred to herein as a "melter");

[0013] FIG. 2 is a schematic diagram illustrating an electrode assembly and thermal length measurement assembly for use in the melting furnace of FIG. 1; [0014] FIG. 3 is a schematic diagram illustrating another electrode assembly and thermal length measurement assembly logic;

[0015] FIG. 4 is a schematic diagram illustrating an assemblage of multiple electrode blocks; and

[0016] FIG. 5 is an exemplary plot of thermal conductivity versus temperature for use in determining electrode length.

DETAILED DESCRIPTION

[0017] Disclosed herein are apparatuses for melting batch materials. The apparatuses include a vessel and at least one electrode assembly disposed within the vessel that includes an electrode. A temperature sensor assembly includes temperature sensors provided in the electrode to provide indications of temperature within the electrode at known locations. A position of a hot face of the electrode can be determined by the measurement module from the signals indicative of temperature, knowledge of the thermal conductivity of the electrode material as a function of temperature and an estimate of temperature at the hot face of the electrode.

[0018] As used herein, the term "hot face" refers to the end face nearest or in contact with batch materials within a melting furnace. The term "cold face" refers to the end face farthest from the melt material within the melting furnace and is generally lower in temperature than the hot face by virtue of being removed from the batch materials. Due to the temperature difference between the hot face and the cold face, heat transfer occurs through the electrode from the hot face toward the cold face.

[0019] Embodiments of the disclosure will be discussed with reference to FIG. 1, which depicts an exemplary furnace 100 for melting batch materials 105. The melting furnace 100 can include a vessel 110, which can comprise, in some embodiments, an inlet 115 and an outlet 120. Batch materials 105 can be introduced into the vessel 110 by way of the inlet 115. The batch materials can then be heated and melted in the vessel by any suitable method or their combination, e.g., conventional melting techniques such as by contact with the side walls 125 and/or bottom 130 of the vessel 110, which can be heated by combustion burners (not shown) in the vessel, and/or by contact with electrodes 140. The melted batch materials 135 can flow out of the vessel 110 by way of the outlet 120 for further processing.

[0020] The term "batch materials" and variations thereof are used herein to denote a mixture of precursor components which, upon melting, react and/or combine to form the final desired material composition. The batch materials can, for example, comprise glass precursor materials, or metal alloy precursor materials, to name a few. The batch materials may be prepared and/or mixed by any known method for combining precursor materials. For example, in certain non- limiting embodiments, the batch materials can include a dry or substantially dry mixture of precursor particles, e.g., without any solvent or liquid. In other embodiments, the batch materials may be in the form of a slurry, for example, a mixture of precursor particles in the presence of a liquid or solvent.

[0021] According to various embodiments, the batch materials may include glass precursor materials, such as silica, alumina, and various additional oxides, such as boron, magnesium, calcium, sodium, strontium, tin, or titanium oxides. For instance, the glass batch materials may be a mixture of silica and/or alumina with one or more additional oxides. In various embodiments, the glass batch materials include from about 45 to about 95 wt% collectively of alumina and/or silica and from about 5 to about 55 wt% collectively of at least one oxide of boron, magnesium, calcium, sodium, strontium, tin, and/or titanium.

[0022] The batch materials can be melted according to any suitable method, e.g., conventional glass and/or metal melting techniques. For example, the batch materials can be added to a melting vessel and heated to a temperature ranging from about 1100 °C to about 1700 °C, such as from about 1200 °C to about 1650 °C, from about 1250 °C to about 1600 °C, from about 1300 °C to about 1550 °C, from about 1350 °C to about 1500 °C, or from about 1400 °C to about 1450 °C, including all ranges and sub-ranges therebetween. The batch materials may, in certain embodiments, have a residence time in the melting vessel ranging from several minutes to several hours to several days, or more, depending on various variables, such as the operating temperature and the batch volume, and particle sizes of the batch material constituents. For example, the residence time may range from about 30 minutes to about 3 days, from about 1 hour to about 2 days, from about 2 hours to about 1 day, from about 3 hours to about 12 hours, from about 4 hours to about 10 hours, or from about 6 hours to about 8 hours, including all ranges and sub-ranges therebetween.

[0023] In the case of glass processing, the molten glass batch materials can subsequently undergo various additional processing steps, including fining to remove bubbles, and stirring to homogenize the glass melt, to name a few. The molten glass can then be processed, e.g., to produce a glass ribbon, using any known method, such as fusion draw, slot draw, and float techniques. Subsequently, in non-limiting embodiments, the glass ribbon can be formed into glass sheets, cut, polished, and/or otherwise processed.

[0024] The vessel 110 can be formed of any insulating or heat-resistant material suitable for use in a desired melting process, for example, refractory materials such as zircon, zirconia, alumina, magnesium oxide, silicon carbide, silicon nitride, and silicon oxynitride, precious metals such as platinum and platinum alloys, and combinations thereof. According to various embodiments, the vessel 110 can include an outer wall or layer with an interior lining of heat- resistant material such as a refractory material or precious metal. The vessel 110 can have any suitable shape or size for the desired application and can, in certain embodiments, have, for example, a circular, oval, square, or polygonal cross-section. The dimensions of the vessel, including the length, height, width, and depth, to name a few, can vary depending on the desired application. Dimensions can be selected as appropriate for a particular manufacturing process or system.

[0025] While FIG. 1 illustrates the electrodes 140 attached within the side walls 125, it is to be understood that the electrodes can be configured within the vessel 110 in any orientation and can be attached to any wall of the vessel 110, such as the roof or bottom of the vessel. Moreover, while FIG. 1 illustrates three electrodes 140, it is to be understood that any number of electrodes may be used as required or desired for a particular application. Further, while FIG. 1 illustrates a vessel 110 comprising an inlet 115 and an outlet 120, which can be suitable for continuous processing, it is to be understood that other vessels can be used, which may or may not include an inlet and/or outlet, and which can be used for batch or semi-batch processing.

[0026] The electrodes 140 can have any dimension and/or shape suitable for operation in a melting furnace. For instance, in some embodiments, the electrodes 140 can be shaped as rods or blocks having end surfaces that are about flush with the furnace walls with opposite end surface located at our outside the furnace walls creating a temperature differential through the electrodes 140 between the opposite end surfaces. The electrodes 140 can have any suitable cross-sectional shape, such as square, circular, or any other regular or irregular shape. Moreover, the initial length of the electrodes 140 can vary depending on the application and/or size of the melting vessel. In some non- limiting embodiments, the electrodes 140 can have an initial length ranging from about 5 cm to about 200 cm, such as from about 20 cm to about 175 cm, from about 30 cm to about 150 cm, from about 40 cm to about 125 cm, from about 50 cm to about 100 cm, or from about 60 cm to about 75 cm, including all ranges and subranges therebetween. Further, the elctrode may have a width and/or height greater than the initial length, such as about 25 cm or more, such as about 40 cm or more, such as about 50 cm or more.

[0027] The electrodes 140 can comprise any material suitable for the desired melting application. For example, the electrode material can be selected such that the normal wear or erosion of the electrode 140 during operation has little or no detrimental impact on the batch composition and/or final product. In various non-limiting embodiments, such as a glass melting operations, the electrode can include one or more oxides or other materials that can be present in the final glass composition. For example, the electrode can include an oxide already present in the batch materials (e.g., nominally increasing the amount of the oxide in the final product) or an oxide not present in the batch materials (e.g., introducing small or trace amounts of oxide into the final composition). By way of non-limiting example, the electrode can include, e.g., stannic tin oxide, molybdenum oxide, zirconium oxide, tungsten, molybdenum zirconium oxide, platinum and other noble metals, graphite, silicon carbide, and other suitable materials and alloys thereof. [0028] According to various embodiments of the disclosure, the vessel 110 can comprise one or more electrode assemblies comprising an electrode 140 and a temperature sensor assembly coupled to the electrode. As used herein, the term "temperature sensor," "temperature probe," and variations thereof are intended to denote any component that generates a measurable signal or input indicative of temperature. For instance, in non-limiting embodiments, the temperature sensor assembly can include a temperature sensor that produces a voltage when the temperature of one of its temperature measurement points differs from the temperature of another temperature measurement point in a process known as the thermoelectric effect.

[0029] As used herein the term "coupled to" and variations thereof is intended to denote that a temperature sensor assembly is in physical contact with an electrode. The temperature sensor assembly can have a temperature measurement point, for example, located within the electrode, for instance, inside a hole or channel drilled into or otherwise formed in the electrode.

[0030] Referring to FIG. 2, an embodiment of an electrode assembly 200 for use in heating a vessel in a manner described above is illustrated and includes an electrode 212 that has a hot face 214 that is in contact with molten batch materials M and insulated by insulator 215 (e.g., the furnace wall and/or other insulator material) on all sides except at the hot face 214. A thermal length measurement assembly 202 is configured to provide an indication of electrode length L_E of the electrode 212 from a predetermined location. The thermal length measurement assembly 202 may include a temperature sensor assembly 204. Any suitable temperature assembly may be used, such as a ceramic-sheathed thermocouple or other sheathed thermocouple configured to withstand temperatures of at least 1500 °C, such as at least 2000 °C or more, and further such as at least 3000 °C or more. In some embodiments, the temperature sensor assembly 204 includes temperature sensors 208 and 210 defining temperature measurement points A and B, respectively, that are located within the electrode 212 of the electrode assembly 200. The temperature measurement points A and B are spaced apart a known distance along the length L_E of the electrode 212. [0031] The temperature sensors 208 and 210 can be disposed within the electrode 212, such as provided through a side of the electrode 212 (and insulator 215) or otherwise provided within the electrode 212. The temperature measurement points A and B correspond to locations x₁ and x₂ along an x-axis of the electrode 212. The x-axis extends generally between the hot face 214 and cold face 217 and substantially perpendicular thereto, along which the electrode length L_E may be measured. The hot face 214 of the electrode 212 corresponds to location x_g, the location of which can be provided by the thermal length measurement assembly 202. Another temperature sensor assembly 216 or same temperature sensor assembly 204 including temperature sensor 218 defining temperature measurement point G can be provided to provide an indication of temperature of the molten bath materials M, which is representative of the temperature at the hot face 214.

[0032] The temperature sensor assemblies 204, 206 (and 216) each include a communication line 220 that is used to direct signals indicative of temperatures at locations x₁ , x₂ and x_g to the measurement module 222. Communication may be provided between the temperature sensor assemblies 204, 206 and 216 either wired and/or wirelessly. Further, communication may be provided either wired or wirelessly from the measurement module 222 to one or more devices external to the measurement module 222, such as smart phones or computers, for example, through an internet (wide area networks) and/or WiFi (local area networks), Bluetooth®, near field (NFC), etc. Accordingly, a network may facilitate communication between two or more devices via an intermediary device or without an intermediary device (i.e., directly).

[0033] The measurement module 222 can include a memory component 224 and a processor component 226. The memory component 224 can save predetermined data, such as contact locations (e.g., x₁, x₂ and x_g) and/or distances therebetween, previously determined temperature readings, previously determined hot face measurements, maintenance routines, etc. The memory component 224 can also include logic that can be performed by the processor component 226 to perform an electrode length L_E determination, the details of which are described below.

[0034] Electrode Length Determination Assuming that the temperature depends only on one coordinate x, the heat flux

In a stationary case, the state of a one-dimensional system does not change with time. Following from energy conservation law, the heat flux j is a constant, not depending on coordinate x. Multiplying Equation (1) by dx and integration over x gives

where, I(T) is an integral function of K(T):

Let the temperature be known at two points: then Equation (2)

becomes

The position of location x_g with known temperature T_g can be found from Equations (4) in the form

Equation (5) is valid for any dependence K(T). Note that the integral thermal conductivity I(T) is contained in Equation (5) only as a ratio of differences. Therefore, adding an arbitrary constant to I(T) or multiplying it by any arbitrary constant factor will not change the distance prediction for the position of the hot face 214 (x_g).

[0036] Measurement of Thermal Conductivity

[0037] To obtain the function I(T) from experiment, Equation (2) can be rewritten as

where, A and B are arbitrary constants, the values of which are irrelevant for the electrode length prediction. The additive constant B is going to be subtracted out because Equation (5) contains only difference of the thermal conductivity antiderivatives of I(T). The multiplicative constant A can be cancelled since Equation (5) contains only a ratio of linear combinations of I(T). Assigning and B = 0 results in

Thus, the function I(T) can be interpolated from measurements of temperature at multiple locations inside the electrode using Equation (7) as an inverse function of T(x). Knowledge of the actual heat flux is not required. The sides of the electrode should be well insulated to approximate one-dimensional heat transfer.

[0038] FIG. 3 illustrates an approximation of the function I(T) for temperatures measured at discrete locations x₁ where, i = 1 , 2, n using temperature assemblies in a fashion similar to those described above. Interpolating points x as a function of temperature gives an approximation of the function I(T) that can be used by the measurement module 222 (FIG. 2) to make an electrode length LE determination. When only two temperature measurement points A and B internal to the electrode 212 are used as in FIG. 2, it can be beneficial to provide an increased distance between the locations x a₁ nd x₂ along the x-axis to aid in accuracy of end point determination through extrapolation beyond location x₂. However, the distance between the locations x₁ and x₂ along the x-axis is limited by the unknown and decreasing location x_g. In some embodiments, more than two temperature measurement points and corresponding temperature sensor assemblies may be used. Insulation 215 of all sides of the electrode 212 can create more of a one-dimensional temperature distribution. Any suitable insulation 215 may be used depending on possible interactions between components of the system. Insulation material examples include non-conductive materials, such as ceramic and glass materials (e.g., glass, alumina, fused silica, etc.).

[0039] The measurement module 222 (FIG. 2) may also monitor for an electrode length L_E approaching a predetermined minimum electrode length. For example, the measurement module 222 may sound an alarm, provide a visual indication and/or even halt operations should an electrode length L_E reach one or more predetermined minimum electrode lengths. In some embodiments, the audio, visual and/or operational alarm conditions may be different or occur at different stages as predetermined minimum electrode lengths are detected. Exemplary minimum electrode lengths may be about 100 mm or less, such as about 75 mm or less, such as about 60 mm or less, such as about 50 mm or less, such as about 50 mm or less, including all ranges and subranges therebetween.

[0040] Referring to FIG. 4, while FIGS. 2 and 3 depict a single electrode block, multiple electrode blocks 240 forming an assemblage 250 may be provided, each electrode block having temperature sensor assemblies and contact locations, as described herein. Further, the measurement module 222 of FIG. 2 or multiple measurement modules may be used to detect electrode length of the multiple electrode blocks.

[0041] One-dimensional temperature distributions are discussed above where heat flows primarily axially through the electrode. However, in instances where the electrode is relatively long, e.g., in the beginning of electrode use, the heat flow may not be accurately represented by a one-dimensional model. Using numerical calculations of computer modeling, an electrode length L_E determination can be made using temperature values and an estimate of the hot face temperature. Example

[0042] Consider the case when thermal conductivity can be approximated by function In this case, I(T) is

proportional toK(T) . Referring to FIG. 5 for illustration, the first temperature sensor is located at 25 mm and the second sensor is located at 53 mm from the cold face. If first temperature sensor measures

and the glass temperature is equation (5)

will give the length of the electrode to be 74 mm.

[0043] The above-described thermal length measurement assemblies and associated methods can utilize detected temperature values along the length of the electrode, knowledge of thermal conductivity of the electrode material as a function of temperature and an estimate of the electrode hot face temperature as an indication of electrode length. Advantageously, as the electrode length decreases, the accuracy of the thermal length measurement processes described herein can increase. Online measurements of electrode length can be monitored without draining the melt material and halting melting operations. The thermal length measurement assemblies can be retrofitted onto electrodes used in currently available me Iters. The above-described thermal length measurement assemblies and associated methods can detect electrode lengths without introducing materials to the melt, which can contaminate, for example, glass produced or alter melt properties. The above-described thermal length measurement assemblies and associated methods can be applicable to a variety of electrodes and melt types.

[0044] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A method of indicating a length of an electrode for an apparatus that melts batch materials, the method comprising:

providing a first signal indicative of temperature at a first temperature measurement point positioned along the electrode using a first temperature sensor;

providing a second signal indicative of temperature at a second temperature measurement point positioned along the electrode using a second temperature sensor; and

determining an electrode length to a hot face of the electrode based on the first and second signals.

2. The method of claim 1 further comprising a measuring module receiving the first signal indicative of temperature at the first temperature measurement point and the second signal indicative of temperature at the second temperature measurement point, the measuring module determining the electrode length to the hot face of the electrode based on the first and second signals.

3. The method of claim 2, wherein the measuring module measures the electrode length to the hot face of the electrode based on location information of the first temperature measurement point and the second temperature measurement point.

4. The method of claim 3, wherein the measuring module measures the electrode length to the hot face of the electrode based on temperature information at the hot face of the electrode.

5. The method of claim 4, wherein the measuring module measure the electrode length to the hot face of the electrode based on thermal conductivity information of material forming the electrode as a function of temperature.

6. The method of claim 2 further comprising entering location information of the first temperature measurement point and the second temperature measurement point into memory of the measuring module.

7. The method of claim 1 further comprising:

inserting the first temperature sensor into the electrode to define the first temperature measurement point; and

inserting the second temperature sensor into the electrode to define the second temperature measurement point.

8. The method of claim 1 further comprising:

providing a third signal indicative of temperature at a third temperature measurement point positioned along the electrode using a third temperature sensor; and

determining the electrode length to the hot face of the electrode based on the first, second and third signals.

9. The method of claim 1 , wherein the step of determining the electrode length to the hot face of the electrode based on the first and second signals uses thermal conductivity of material forming the electrode.

10. An apparatus for melting batch materials, comprising:

a vessel;

an electrode located in the vessel and having an electrode length measured along an axis between a hot face and cold face of the electrode; and

a thermal length measurement assembly comprising:

a first temperature sensor arranged and configured to provide a first signal indicative of a temperature at a first temperature measurement point positioned along the electrode; and a second temperature sensor arranged and configured to provide a second signal indicative of a temperature at a second temperature measurement point positioned along the electrode, the first and second signals used to determine the electrode length.

11. The apparatus of claim 10 further comprising a measurement module including a processor that receives the first and second signals indicative of temperature at the first and second temperature measurement points, the measurement module including logic executable by the processor that determines the electrode length based on the first and second signals indicative of temperature.

12. The apparatus of claim 11, wherein the measurement module comprises a memory component that saves position information of the first temperature measurement point and the second temperature measurement point in memory.

13. The apparatus of claim 10 further comprising an insulator provided about the electrode.

14. The apparatus of claim 10, wherein the electrode has a width that is greater than an initial length of the electrode.

15. The apparatus of claim 10, wherein the electrode has a height that is greater than an initial length of the electrode.

16. The apparatus of claim 10 further comprising a third temperature sensor arranged and configured to provide a third signal indicative of a temperature at a third temperature

measurement point positioned along the electrode, the first, second and third signals used to determine the electrode length.

17. A thermal length measurement assembly for an apparatus for melting batch materials, the thermal length measurement assembly comprising: a temperature sensor arranged and configured to provide a signal indicative of a temperature at a temperature measurement point positioned along a electrode; and

a measurement module including a processor that receives the signal indicative of temperature at the temperature measurement point, the measurement module including logic executable by the processor that determines an electrode length to a hot face of the electrode based on the signal indicative of temperature.

18. The thermal length measurement assembly of claim 17, wherein the temperature sensor is a first temperature sensor and the temperature measurement point is a first temperature measurement point, the apparatus further comprising a second temperature sensor arranged and configured to provide a signal indicative of a temperature at a second temperature measurement point positioned along the electrode.

19. The thermal length measurement assembly of claim 17, wherein the measurement module comprises a memory component that saves position information of the first temperature measurement point and the second temperature measurement point in memory.

20. The thermal length measurement assembly of claim 17, wherein the logic executable by the processor that determines the electrode length to the hot face of the electrode based on the signal indicative of temperature using thermal conductivity of material forming the electrode.