Method and apparatus for evaluating the state of a material in a metallurgical vessel

Abstract

Disclosed are an apparatus and method for assessing the condition of refractory material in metallurgical vessels, including furnaces and ladles. External structures at least partially surrounding the refractory material inhibit the propagation of radio frequency signals. The apparatus and method operate to use the radio frequency signals to identify defects and determine erosion profiles, thickness of the refractory material, and the level or rate of ingress of molten material into the refractory material. The apparatus includes an antenna embedded within the refractory material or disposed within a chamber of the vessel designed to collect data related to the propagation of radio frequency signals transmitted by the antenna within the refractory material. Furthermore, signal processing methods enable the identification of the condition of the vessel's interior walls due to operational wear, operating hours, and the presence of defects, cracks, corrosion, and erosion, thereby improving the vessel's operational life and maintainability.

Description

Technical Field

[0001] (Related Application) This application claims priority based on, and incorporates by reference, the specification of the co-pending U.S. Provisional Patent Application No. 63 / 005,499, filed Apr. 6, 2020, by the inventors of this specification, entitled "Methods and Apparatus for Evaluating the Condition of Materials in a Metallurgical Vessel".

[0002] The present invention generally relates to systems and methods for evaluating the condition of materials. More specifically, the present invention relates to sensor systems and methods for monitoring and determining the condition of refractory materials using radio frequency (RF) signals.

Background Art

[0003] Multiple evaluation methods and apparatuses for measuring the properties of a particular material during or after its formation using RF signals have been disclosed in various industries. Surface characteristics, internal homogeneity, residual material thickness, rate of erosion of the material, rate of ingress of a first material into a second material are important attributes that may require monitoring and evaluation. Primarily, the type and placement of sensors around the material being evaluated play an important role in determining to what extent these attributes can be measured.

[0004] In particular, the metallurgical industry uses large containers such as furnaces and ladles to melt the raw materials used in the process. These are important facilities for manufacturers from the perspectives of cost and operational functionality. At high operating temperatures, these furnaces and ladles are configured to form a refractory melting chamber using refractory materials having a high melting temperature and good insulating properties so as to minimize internal heat loss. However, the inner refractory walls of the furnaces and ladles deteriorate during operation. The effects of this deterioration include refractory erosion, refractory corrosion, stress cracking, and diffusion of the refractory material into the molten material. On the other hand, when the refractory material deteriorates over time, there is a high risk of leakage of the molten material through the refractory wall, where the molten material may enter the refractory material, accelerate the deterioration process, and cause significant damage.

[0005] Specifically, the use of microwaves to measure the thickness of materials such as furnace walls has been disclosed in the prior art as described in U.S. Patent No. 6,198,293 by Woschof et al. and U.S. Patent No. 9,255,794 by Walton et al. However, these attempts face certain challenges and problems. In particular, these attempts to determine the furnace wall thickness of high-temperature furnaces have a significant signal loss problem regarding the evaluation of the inner surface of the refractory material, especially when using microwave signals transmitted from the outside of the furnace in a relatively high-frequency band. Similarly, signals in a relatively low-frequency band have losses, and there are limitations to the bandwidth and resolution required by existing systems. Furthermore, in placing the components of the system near the surface of the refractory material to be evaluated, spurious signal reflections make it difficult to separate the target reflection signal, thus making it even more difficult to evaluate the inner surface or internal state of these materials. One of the major challenges is that the furnace wall becomes highly electrically conductive as the temperature increases. Therefore, signals passing through the high-temperature furnace wall have significant losses, and the detection of these signals is difficult. In addition, in many cases, the monitoring sensors require direct physical access to the refractory material under evaluation and are particularly sensitive to the presence of certain nearby objects formed of metallic materials.

[0006] As described in U.S. Patent No. 10,151,709 by Bayram et al., U.S. Patent No. 9,880,110 by Lyuge et al., and U.S. Patent No. 10,054,367 by Bayram et al., other efforts have been made to evaluate the condition of materials using electromagnetic waves by suppressing the levels of losses and spurious signals related to the evaluation of refractory materials. However, these systems are mainly aimed at improving the multiple reflection effects of electromagnetic waves used to suppress the clutter associated with the received signals. In addition, these attempts have focused on independent systems that transmit electromagnetic waves from the outside of the furnace to the refractory material. As a result, these efforts become ineffective in cases where the furnace or ladle is surrounded by an outer shell or a specific support structure, where these shells and structures are formed of materials with high conductivity and impede the propagation of electromagnetic waves through them, or in applications in difficult-to-access areas where the external evaluation system cannot be properly installed.

[0007] The specifications of each of the aforementioned referenced U.S. patents are hereby incorporated by reference in their entirety.

[0008] Particularly in the metallurgy of steel, blast furnaces or electric arc furnaces are used to carry out metallurgical reactions so as to achieve rapid melting of steel and adjust the final chemical composition of the melt. Subsequently, the molten steel is transported to ladles for further refining. The treatment of steel in ladles involves the addition of reducing agents, slag formers, desulfurizing agents, and alloying agents. These additives, together with the high temperatures at which the ladles operate, contribute to significant stress, wear, and degradation on both the inner walls and the bottoms of the ladles, and are a major cause thereof. In particular, electric arc furnaces and ladles with a capacity of 50 tons or more are mainly used for steel production. These ladles need to be subject to maintenance for residue removal and inspection, and are sometimes repaired on a weekly basis. Similarly, steel production may involve blast furnaces that perform continuous melting operations. These furnaces have a steel lining on the outside and refractories that interact with the molten material on the inside. When the refractories deteriorate, maintenance of the blast furnace is required to prevent unplanned production interruptions.

[0009] Furthermore, the flow of molten materials such as molten steel erodes and deteriorates the inner surfaces of metallurgical materials at high temperatures, leading to a high risk of leakage of molten steel through the walls of refractory materials and / or significant damage to the outer shell of the furnace. Major leaks of molten steel through gaps and cracks in the furnace walls may require at least 30 days of production interruption for cooling, repair, and restart before the furnace can be returned to the operating mode. Additionally, molten steel leaks can cause significant damage to the equipment around the furnace, and most seriously, pose risks to the health and lives of workers. For these reasons, in many cases, furnace overhauls are carried out significantly earlier than when they are actually required. This results in high costs for producers in terms of initial investment and reduced production capacity during the furnace operation period.

[0010] Therefore, it is important for furnace operators to plan maintenance efficiently and monitor the deterioration of the refractory materials in the furnace walls to extend the operating life of the furnace and schedule furnace shutdowns when truly necessary. The life of a furnace is affected by multiple factors, including its operating age, average operating temperature, temperature rates in heating and cooling, range of operating temperatures, number of operating cycles, type and quality of refractory materials, and the amount and type of molten materials and additives (load) used in the furnace. Each of these factors has an uncertainty that makes it difficult to generate an accurate prediction of the expected life of the furnace and the timing for performing the corresponding maintenance tasks.

[0011] Currently, there are no established methods and devices for deterministically and effectively measuring the thickness and erosion profile of the inner wall, or the level or rate of entry of molten materials into the refractory materials surrounding the furnace or ladle having an outer shell. This inhibits the ability to accurately predict both the operating life and maintenance schedule of many furnaces and ladles. As a result, manufacturers may experience the need to conservatively shut down the furnace for reconstruction to prevent unforeseen leakage of molten materials through the furnace wall, severe damage to the outer shell of the furnace, or the likelihood of leakage or severe damage based on the manufacturer's experience regarding the expected life of the furnace.

[0012] Another important issue is that the materials used to form the refractory chamber of the furnace have internal defects that are not visible by surface inspection. This leads to a shortening of the furnace life and poses a significant risk during furnace operation. Therefore, it is common sense for furnace operators to build a lattice structure surrounding the outer refractory wall of the furnace to minimize the impact of furnace failures and extend the operating life of the furnace. Typically, this lattice has a set of elements such as plates or bars formed of steel or materials having relatively high electrical conductivity, and are arranged substantially parallel and orthogonal to each other to form a grid.

[0013] The lattice provides structural support not only for deteriorated refractory walls but also for additional refractories installed in the furnace as preventive or corrective maintenance means. In addition, by absorbing and dissipating heat, the lattice contributes to cooling the refractory material. However, the lattice spacing between adjacent elements can be on the order of a few centimeters, which makes it difficult to provide direct access to the furnace wall required by many sensors using high-frequency signals, or results in signal interference for sensors that cannot physically fit within the lattice spacing. Therefore, the inhibition of the effective integration of sensors such as antennas, and existing or installed lattices surrounding the refractory material of the furnace, may lead to the inability to predict the remaining service life and the maintenance plan of the furnace or ladle.

[0014] Therefore, there is a need in the art for a method and apparatus that can remotely evaluate the condition of refractory materials forming part of a furnace or ladle through the measurement of propagating RF signals, avoiding the problems of the prior art methods and apparatus. SUMMARY OF THE INVENTION

[0015] An apparatus and method for evaluating and monitoring the condition of refractory materials forming part of a metallurgical vessel such as a refractory furnace or ladle, in which an external structure at least partially surrounding the refractory material inhibits the propagation of high-frequency signals, are disclosed herein. One or more aspects of the exemplary embodiments provide advantages while avoiding the disadvantages of the prior art. The apparatus and method operate using high-frequency signals to identify defects and determine erosion profiles, the thickness of the refractory material, and the level or rate of entry of molten material into the refractory material. The apparatus has an antenna disposed within a chamber of a container designed to collect data related to the propagation of high-frequency waves embedded in the refractory material or transmitted to the refractory material by the antenna. Further, signal processing techniques make it possible to determine the condition of the inner wall of the container due to operational wear, operating time, defects, cracks, corrosion, erosion, so as to improve the service life and maintainability of the container.

[0016] The external structure that at least partially surrounds the refractory material of the container may be part of the container, as is usual in metallurgical ladles and certain furnaces, an added structure such as a lattice structure that provides additional mechanical support to an existing furnace, or a neighboring structure that inhibits access from outside the container for correctly setting the transmission of RF signals inside the refractory material. Additionally, within the scope of the present invention, the container may include a furnace or a ladle, and the terms furnace or ladle are used interchangeably since the present invention is applicable to any one or both of them without distinction.

[0017] The antenna transmits an RF signal to the region of interest of the material to be evaluated. When the RF signal impinges on such a region, it scatters, is at least partially reflected through remote discontinuities, and is at least partially transmitted. Remote discontinuities may be any void, defect, the presence of different materials within the material to be evaluated, or any interface between two different materials including air. The scattered RF signal is received by the same or a different antenna and then measured, recorded, processed by a computer-type processor, and timed, with reference to the transmitted RF signal or the RF signal scattered from an originally installed discontinuity surface such as the interface between the antenna and the surface of the material under evaluation.

[0018] A computer-type processor has executable computer code configured to generate either time-domain data or frequency-domain data that is converted to time-domain data, and to measure a received scattered RF signal that calibrates the time-domain data to range-domain data. In particular, when the magnitude of the clutter is less than the magnitude of the RF signal scattered from a distant discontinuity of the material under evaluation, the computer-type processor identifies the peak level of the magnitude associated with this discontinuity and determines the distance from this discontinuity to the position associated with the reference RF signal. One or more evaluations on the region of interest of the material under evaluation may provide the thickness of the material, the position of a particular defect, or the position of an adhered element within the material. Further, time-domain and / or frequency-domain signal processing techniques, or a combination of both, may be used to determine and visualize the state of the region of interest being evaluated.

[0019] In the present invention, the antenna is preferably embedded in a refractory material so as to fit the refractory material without having a gap between the antenna radiation end and the refractory material, using one or more cast refractory bricks. However, this can only be carried out during the initial construction or major repair of the vessel. Instead, other embodiments of the present invention have an antenna disposed within the chamber of the vessel. As a result, the refractory material of an existing vessel may also be evaluated. In addition, different mounting mechanisms may include an antenna to physically position the antenna within the chamber of the vessel.

[0020] Evaluating and measuring the erosion profile and thickness conditions of different materials, including refractory materials that form part of a metallurgical vessel, and measuring the level or rate of entry of molten material into the refractory material, involves the step of installing at least one antenna embedded in the material or placed within the chamber of the vessel. The method further includes the steps of transmitting at least one RF signal to a region of interest of the material under evaluation and receiving at least one RF signal incident on such a region. The method includes measuring, recording, transferring, or processing the magnitude and phase of at least one RF signal to determine the state of the material under evaluation based on the results of the processed data.

[0021] By embedding at least a part of a device such as an antenna in the refractory material or placing the antenna within the chamber of a metallurgical vessel, the device and method identify defects in these materials and measure the erosion profile of the inner surface and the entry of molten material into the refractory material. Thus, the prediction of the remaining operating time of the vessel becomes more accurate and, in practice, may lead to extending the life of the vessel. This results in a more efficient and accurate planning for better managing the costly processes of repairing, relining, or replacing the metallurgical vessel, along with a significant reduction in the level of risk of operating interruptions, leakage of molten material, or significant damage to the metal outer shell of the vessel. Therefore, the device and method enable a more efficient evaluation, management, diagnosis, or monitoring of one or more conditions that can extend the operating life of expensive and dangerous equipment such as metallurgical vessels and lead to an improvement in the maintenance plan.

[0022] The various advantages of the present invention may be better understood by those skilled in the art with reference to the accompanying drawings.

Brief Description of the Drawings

[0023]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 3C

Figure 4

Best Mode for Carrying Out the Invention

[0024] The following description of specific embodiments of the present invention is provided to enable the implementation of examples of the present invention, and is not intended to limit the desired embodiments, but rather to illustrate specific examples thereof. Those skilled in the art will recognize that the disclosed ideas and specific embodiments can be readily used as a basis for modifying or designing other methods and systems for implementing the same purpose as the present invention. Those skilled in the art will recognize that such equivalent structures do not depart from the broadest ideas and scope of the invention.

[0025] According to certain aspects of embodiments of the present invention, FIGS. 1A through 1C show various aspects of apparatus 10 used to show the state of furnace 12. In this example, furnace 12 has an outer shell of steel. More specifically, apparatus 10 evaluates the state of refractory material 14 that normally at least partially surrounds chamber 15 of furnace 12. In other words, refractory material 14 is disposed in one or more layers between chamber 15 where melting of a material such as steel occurs and the bottom and outer sides of furnace 12 that include the outer steel shell. Typically, the various layers of refractory material 14 are formed using bricks that are arranged adjacent to each other from the bottom to the top of furnace 12. Thus, refractory material 14 forms one or more walls that surround the crucible or chamber 15 of furnace 12, where the remote surface of the inner wall of refractory material 14 means the area of the wall or surface adjacent to chamber 15 of furnace 12. Similarly, the outer wall of refractory material 14 is defined by the wall of refractory material 14 that is disposed furthest from chamber 15 of furnace 12. Additionally, one or more sets of antennas having at least one antenna may be embedded within refractory material 14. Each set of antennas may be controlled by a second computer-type processor, and a first computer-type processor controls all of the second computer-type processors.

[0026] In this particular embodiment, the apparatus 10 has a set of three antennas 17a, 17b, 17c embedded in the refractory material 14. Desirably, the antennas 17a, 17b, 17c are designed and physically configured to operate while embedded in one of the layers of the refractory material 14. As a result, the antennas 17a, 17b, 17c are substantially impedance-matched to the refractory material 14, and no additional impedance-matching measures are required. More desirably, the antennas 17a, 17b, 17c are embedded in the refractory material 14 such that the transmission signals from the antennas 17a, 17b, 17c propagate through the refractory material 14 to reach most of the contour 16 that defines the boundary between the refractory material 14 and the chamber 15. More desirably, each of the antennas 17a, 17b, 17c is embedded in one or more forged bricks of the refractory material 14. Ideally, in the furnace design, the correct positions of the antennas 17a, 17b, 17c are defined, and the matrix of each of the antennas 17a, 17b, 17c is formed by forging with a set of forgeable refractory bricks that are part of the inner wall of the refractory material 14. Thus, the antennas 17a, 17b, 17c are installed at the predefined positions in the construction of the furnace. Alternatively, the set of forged refractory bricks in which the antennas 17a, 17b, 17c are embedded may be used in the maintenance of the furnace and in the replacement with normal unforged refractory bricks at the predefined positions.

[0027] Furthermore, in this configuration, the refractory bricks are designed to be forged such that the antennas fit into the refractory material so that there is no gap between the radiating edge of the antenna and the refractory material. Therefore, no special measures are required to match the impedance of the antenna to the impedance of the refractory material, as is normal when the antenna is not forged and is installed outside the refractory material.

[0028] Device 10 further includes a transceiver 18 capable of transmitting and receiving RF signals, and a set of cables 19a, 19b, 19c that couple the transceiver 18 to each of the antennas 17a, 17b, 17c. Device 10 further includes a data storage device for storing data and a single computer-type processor, both of which may be integrated into the transceiver 18. The stored data may be retrievable using a portable memory drive, a cable, or other electronic means known to those skilled in the art. Further, at least in part, the transceiver 18 may be integrated with one or more of the antennas 17a, 17b, 17c. Thus, based on the degree of integration of the transceiver 18 and the antennas 17a, 17b, 17c, the refractory bricks and the outer steel shell of the furnace 12 are physically configured to allow routing of the set of cables 19a, 19b, 19c, or other control, power, or communication lines, from the antennas 17a, 17b, 17c or at least a portion of the transceiver 18, outside of the vessel 12. These physical configurations may include grooves, holes, recesses, cuts, ducts, or passages. Additionally, the set of cables 19a, 19b, 19c is required to be able to withstand high temperatures of at least 500°C. The transceiver 18, particularly the components of the storage device and the computer-type processor, are not shown as they are not important for the description of this embodiment.

[0029] In the evaluation of the state of the refractory material 14, more specifically, in the evaluation of the state of the contour 16 of the refractory material 14, the RF signal transmitted from the transceiver 18 and reaching the contour 16 through the antennas 17a, 17b, 17c is partially reflected. This reflection is caused by the discontinuity of the medium at the boundary between the refractory material 14 that the propagating RF signal faces and the material in the chamber 15 of the furnace 12. Desirably, the antennas 17a, 17b, 17c are arranged such that the transmitted signal from the antennas 17a, 17b, 17c is incident on the contour 16 substantially orthogonally in the region where the contour 16 is adjacent to the molten material in the chamber 15 of the furnace 12. More desirably, the antennas 17a, 17b, 17c are physically configured to reduce multiple reflections and probing of the RF signals transmitted or received by the antennas 17a, 17b, 17c to such an extent that detection of the RF signal after being scattered by a distant discontinuity of the refractory material 14 is enabled. Most desirably, the antennas 17a, 17b, 17c are physically configured and arranged such that the transmitted signal from the antennas 17a, 17b, 17c reaches the outer steel shell of the vessel 12 minimally, and the effect of the signal received by the transceiver 18 after being reflected by the outer steel shell of the vessel 12 is minimized.

[0030] Normally, the chamber 15 contains steel or air (when the chamber 15 is empty). The RF signal reflected at the contour 16 is received by the antennas 17a, 17b, 17c and transmitted to the transceiver 18 for further processing, storage, or processing. The transceiver 18 measures the amplitude and phase of the received signal in one or more frequency bands in the range from 0.5 GHz to 70 GHz. Further, in the processing of these signals using one or more signal processing methods in the frequency and / or time domain, the apparatus 10 can determine the shape of the contour 16 and the corresponding thickness of the refractory material 14 along different points of the contour 16. In addition, the apparatus 10 can determine the level and rate of entry of the molten material in the chamber 15 into the refractory material 14.

[0031] Alternatively, the antennas 17a, 17b, 17c may be attached to the refractory material 14 of the container 12 instead of being embedded in the refractory material 14. In either case, each of the antennas 17a, 17b, 17c is in physical contact with the refractory material 14 and preferably has a pyramidal horn antenna having a rectangular cross-section, and a first flare plate having two flare portions along the opposing side edges of the planar portion and the planar portion of the first flare plate, and a second flare plate disposed to face the first flare plate, and the second flare plate has two flare portions along the opposing side edges of the planar portion and the planar portion of the second flare plate. In particular, at least one of the thicknesses of the first flare plate and the second flare plate is changeable, and preferably, the ratio of at least one of the thickness to length of the first flare plate and the second flare plate is in the range of 15% to 85%. In such a configuration, more preferably, each of the antennas 17a, 17b, 17c further has an insulating material disposed in at least a part of the volume region between the first flare plate and the second flare plate and extending beyond the two flare portions along the opposing side edges of the first flare plate and the second flare plate. More preferably, the insulating material has a dielectric constant that matches the dielectric constant of the refractory material 14, and eases the discontinuity of the medium between the insulating material and the refractory material 14. Alternatively, the refractory material itself is used as the insulating material.

[0032] One skilled in the art will recognize that antennas of different types other than horn antennas, and / or antennas with or without smooth rolled edges, may be used in device 10. More specifically, a horn antenna having four flare plates, a horn antenna that is not pyramid-shaped such as conical, or a horn antenna having a cross-section that is not rectangular such as elliptical may be used. Similarly, one skilled in the art will recognize that device 10 may further have various arrangements of RF components such as filters, impedance matching networks, amplifiers, non-coherent detectors, etc., and may further have other test instrumentation used in various ways to effectuate measurement of the transmitted and received RF signals and to perform the functions of transceiver 18 and computer-type processor as known in the prior art. Further, one skilled in the art will recognize that cables 19a, 19b, 19c may be replaced in the wireless system to couple antennas 17a, 17b, 17c to transceiver 18.

[0033] In particular, FIG. 1A shows a side view of a cross-section of furnace 12 showing device 10, where antennas 17a, 17b, 17c are embedded in refractory material 14 that forms part of one wall of furnace 12. Similarly, FIG. 1B shows a bottom view of a cross-section of furnace 12 showing device 10, where antennas 17a, 17b, 17c are embedded in refractory material 14 that forms part of one wall of furnace 12. More specifically, antennas 17a, 17b, 17c are disposed on refractory material 14 in an arrangement that enlarges the evaluable region of contour 16 at the boundary between refractory material 14 and chamber 15.

[0034] Referring to FIG. 1C, a side view of a horizontal cross-section of the furnace 12 showing the apparatus 10 is presented. Antennas 17a, 17b, 17c are embedded in the refractory material 14 that forms part of one wall of the furnace 12, and antennas 17d, 17e, 17f are also embedded in the refractory material 14 that forms part of one wall of the furnace 12. Antennas 17d, 17e, 17f are opposed to antennas 17a, 17b, 17c. In this configuration, the apparatus 10 further has a second transceiver 13 capable of transmitting and receiving RF signals and a set of cables 19d, 19e, 19f that couple the transceiver 13 to the antennas 17d, 17e, 17f respectively. The apparatus 10 further has a second data storage device and a second computer-type processor, both of which may be integrated with the transceiver 13. Further, at least partially, the transceiver 13 may be integrated with one or more of the antennas 17d, 17e, 17f. The components of the transceiver 13, particularly the components of the storage device and the computer-type processor, are not important for the description of the present embodiment and thus will be recognized as not being shown. Those skilled in the art will recognize that the antennas 17d, 17e, 17f may be connected to the transceiver 18 through the cables 19d, 19e, 19f, and thus one transceiver is used for all of the six antennas 17a - 17f.

[0035] Preferably, antennas 17a, 17b, 17c and antennas 17d, 17e, 17f face each other. More preferably, the RF signals transmitted by antennas 17a, 17b, 17c are received by at least one of antennas 17d, 17e, 17f. Most preferably, referring to FIG. 1C, the evaluation of the state of the refractory material 14 using this specific configuration is performed when the chamber 15 of the furnace 12 is at least partially empty, and thus the signal transmitted through the chamber 15 is less attenuated than the signal when the chamber 15 is not empty. This specific configuration may provide additional information regarding the transmitted signal because the transmitted signal from one or more of antennas 17a, 17b, 17c passes through the contour 16 in at least two different regions to one or more of antennas 17d, 17e, 17f. The first region of the contour 16 at the boundary between the refractory material 14 and the chamber 15 is close to one or more of the transmitting antennas 17a, 17b, 17c, and the second region of the contour 16 at the boundary between the refractory material 14 and the chamber 15 is close to one or more of the receiving antennas 17d, 17e, 17f. Those skilled in the art will recognize that each of antennas 17a - 17f may be used as a transmitting or receiving antenna. The main challenge is to direct at least one of the transmitting antennas towards at least one of the receiving antennas.

[0036] Figures 2A through 2C show various aspects of an apparatus 20 used to evaluate the state of a cylindrical furnace 22 according to further aspects of the embodiments. More specifically, the apparatus 20 typically evaluates the state of a refractory material 24 that at least partially surrounds the chamber 25 of the furnace 22. In other words, the refractory material 24 is disposed in one or more layers between the chamber 25 where melting of a material such as steel occurs and the bottom and side walls of the crucible 22. Typically, the various layers of the refractory material 24 are formed using bricks arranged adjacent to each other from the bottom to the top of the crucible 22. Thus, the refractory material 24 forms one or more walls surrounding the chamber 25 of the crucible 22.

[0037] In this particular configuration, the apparatus 20 has one or more antennas disposed within the chamber 25 to form an antenna array 27 when the cooking pot 22 is not operating and is completely or partially empty. Desirably, the antenna array 27 is arranged to propagate within the chamber 25 such that the transmitted signal from the antenna array 27 reaches a majority of the contour 26 that defines the boundary between the refractory material 24 and the chamber 25. More desirably, the antenna array 27 is arranged such that the transmitted signal from the antenna array 27 impinges substantially orthogonally to the contour 26. Most desirably, the antenna array 27 is mounted on a mechanical structure 28 that supports and can adjust the position of the antenna array 27 within the chamber 25 during or between furnace operations.

[0038] Furthermore, the apparatus 20 may further include a controller that can be attached to the structure 28 and programmed by one or more motorized mechanisms to automatically position the antenna array 27. In a preferred embodiment, the structure 28 may be rotated along an axis substantially parallel to the region of the contour 36 under evaluation, or may be installed at various positions such that the antenna array 27 can receive RF signals reflected from all of the region defined by the contour 26. Additionally, the apparatus 20 may further include software that is used to automatically control the position of the structure 28, record and store the measured data, or guide at least a part of the evaluation process step by step to perform a corresponding evaluation of the state of the material.

[0039] The apparatus 20 further includes a transceiver capable of transmitting and receiving RF signals and a set of cables for coupling the antenna array 27 to the transceiver. The apparatus 20 further includes a data storage device and a computer-type processor, both of which may be integrated with the transceiver. Further, at least partially, the transceiver may be integrated with the antenna array 27. The transceiver, the storage device, the computer-type processor, the controller, and the motor are not shown as they are not important for the description of the present embodiment. Further, when applicable, the structure 28 may provide a support mechanism for routing the cables or mounting sensors such as the transceiver, the storage device, the computer-type processor, the controller, the motor, and the laser, LIDAR, or ultrasonic sensor.

[0040] In the evaluation of the state of the refractory material 24, more specifically, in the evaluation of the state of the contour 26 of the refractory material 24, the RF signal transmitted by the antenna array 27 and reaching the contour 26 is partially reflected. This reflection is caused by the discontinuity of the medium faced by the propagating RF signal at the boundary between the chamber 25 and the refractory material 24. The RF signal reflected at the contour 26 is received by the antenna array 27 and transmitted to the transceiver for further processing, storage, and processing as described in the case of the apparatus 10 with reference to FIGS. 1A to 1C.

[0041] Alternatively, instead of being attached to the structure 28, the antenna array 27 may be connected to the refractory material 24 of the cooking pot 22. In either case, as described in the context of the apparatus 10 with reference to FIGS. 1A through 1C, each antenna of the antenna array 27 preferably has a pyramidal horn antenna. One of ordinary skill in the art will recognize that different types of antennas other than horn antennas, and / or antennas with or without smooth rolled edges, may be used in the apparatus 20. More specifically, a horn antenna having four flare plates, a horn antenna that is not pyramidal such as conical, or a horn antenna having a non-rectangular cross-section such as elliptical may be used. Similarly, one of ordinary skill in the art will recognize that the apparatus 20 may further have various arrangements of RF signals such as filters, impedance matching networks, amplifiers, non-coherent detectors, etc., and may further have other test instrumentation used in various ways to effectuate measurement of the transmitted and received RF signals and to perform the functions of a transceiver and a computer-type processor as known in the prior art.

[0042] Specifically, FIG. 2A shows a side view of a lateral cross-section of the cooking pot 22 showing the apparatus 20, where the antenna array 27 is mounted on the structure 28 and is substantially centered in the chamber 25, such that the RF signal transmitted by the antenna array 27 impinges substantially orthogonally onto the area of the contour 26 disposed on the side surface of the chamber 25 of the cooking pot 22. Similarly, FIG. 2B shows a side view of a lateral cross-section of the cooking pot 22 showing the apparatus 20, where the antenna array 27 is mounted on the structure 28 and is substantially centered in the chamber 25, such that the RF signal transmitted by the antenna array 27 impinges substantially orthogonally onto the area of the contour 26 disposed on the bottom surface of the chamber 25 of the cooking pot 22.

[0043] Referring to FIG. 2C, a side view of a lateral cross-section of the cooking pot 22 showing the apparatus 20 is presented. The first antenna array 27 and the second antenna array 29 are mounted on the structure 28 and are substantially disposed at the center of the chamber 25. Thus, the RF signal transmitted by the antenna array 27 impinges substantially orthogonally on the region of the contour 26 located on the sidewall of the chamber 25 of the cooking pot 22. In such a configuration, since the antenna arrays 27, 29 can transmit RF signals to a larger region of the contour 26 as compared to the case where only the antenna array 27 is used as shown in FIG. 2A, the apparatus 20 does not have to rotate or can rotate less.

[0044] FIGS. 3A through 3C show various aspects of an apparatus 30 used to evaluate the condition of a cylindrical cooking pot 32 according to a further aspect of the embodiment. More specifically, the apparatus 30 evaluates the condition of a refractory material 34 that typically at least partially surrounds the chamber 35 of the cooking pot 32. In other words, the refractory material 34 is disposed in one or more layers between the chamber 35 where melting of a material such as steel occurs and the bottom and side surfaces of the cooking pot 32. Typically, the various layers of the refractory material 34 are formed using bricks that are arranged adjacent to each other from the bottom to the top of the cooking pot 32. Thus, the refractory material 34 forms one or more walls surrounding the chamber 35 of the cooking pot 32.

[0045] In this particular configuration, the apparatus 30 has one or more slot antennas that form a slot antenna array 37 along a waveguide 38 through which an RF signal propagates. The slot antenna array 37 and the waveguide 38 are disposed within the chamber 35 when the susceptor 32 is not operating and is completely or partially empty. Desirably, the slot antenna array 37 is arranged such that a transmission signal from the slot antenna array 37 propagates within the chamber 25 such that it reaches a majority of the contour 36 that defines the boundary between the refractory material 34 and the chamber 35. More desirably, the slot antenna array 37 is arranged such that a transmission signal from the slot antenna array 37 impinges substantially orthogonally on all regions of the contour 36. Most desirably, the waveguide 38 is part of a mechanical structure that can support and adjust the position of the slot antenna array 37 within the chamber 35 during operation of the furnace or when the furnace is not operating.

[0046] Furthermore, the apparatus 30 may further include a controller that is attachable to the waveguide 38 and can be programmed by one or more motorized mechanisms to automatically position the slot antenna array 37. In a preferred embodiment, the waveguide 38 may be rotated about an axis substantially parallel to the region of the contour 36 under evaluation and may be positioned at various locations such that the slot antenna array 37 can receive RF signals reflected from all of the region defined by the contour 36. Desirably, the waveguide 38 is a waveguide having an open end such that it further transmits an RF signal substantially orthogonal to the region of the contour 36 disposed at the bottom of the chamber 35 of the susceptor 32. Additionally, the apparatus 20 may further include software that is used to automatically control the position of the structure 28, record and store measured data, or guide at least a part of the evaluation process step by step to perform a corresponding evaluation of the state of the material.

[0047] Apparatus 30 further includes a transceiver capable of transmitting and receiving RF signals, and a set of cables and / or adapters that can couple a waveguide 38 to the transceiver. Apparatus 30 further includes a data storage device and a computer-type processor, both of which may be integrated with the transceiver. Additionally, at least in part, the transceiver may be integrated with the waveguide 38. The transceiver, storage device, computer-type processor, controller, and motor are not shown as they are not important for the description of this embodiment. Further, where applicable, the waveguide 38 may provide a support mechanism for routing cables or mounting sensors such as transceivers, storage devices, computer-type processors, controllers, motors, and lasers, LIDAR, or ultrasonic sensors.

[0048] In the evaluation of the state of the refractory material 34, more specifically, in the evaluation of the state of the contour 36 of the refractory material 34, the RF signal transmitted by the slot antenna array 37 and reaching the contour 36 is partially reflected. This reflection occurs due to the discontinuity of the medium faced by the propagating RF signal at the boundary between the chamber 35 and the refractory material 34. The RF signal reflected at the contour 36 is received by the slot antenna array 37 and transmitted through the waveguide 38 to the transceiver for further processing, storage, and processing as described in the case of apparatus 10 with reference to FIGS. 1A - 1C.

[0049] Alternatively, the waveguide 38 may be attached to the refractory material 34 of the susceptor 32. In either case, each antenna of the slot antenna array 37 preferably has an aperture sized to transmit and receive RF signals on the side of the waveguide 38, as is known in the prior art. One of ordinary skill in the art will recognize that different types and sizes of slot antennas may be used in the apparatus 30. Similarly, one of ordinary skill in the art will recognize that the apparatus 30 may further include various arrangements of RF signals such as filters, impedance matching networks, amplifiers, non-coherent detectors, etc., and may further include other test instrumentation used in various ways to effectuate the measurement of the transmitted and received RF signals and to perform the functions of a transceiver and a computer type processor as is known in the prior art.

[0050] In particular, FIG. 3A shows a side view of a lateral cross-section of the susceptor 32 showing the apparatus 30, where the slot antenna array 37 is mounted on the waveguide 38, and the waveguide 38 is substantially disposed at the center of the chamber 35, such that the RF signals transmitted from the slot antenna array 37 impinge substantially orthogonally on the area of the contour 36 disposed on the side of the chamber 35 of the susceptor 32. Preferably, the waveguide 38 is a waveguide having an open end so as to further transmit RF signals substantially orthogonal to the area of the contour 36 disposed at the bottom of the chamber 35 of the susceptor 32.

[0051] Similarly, FIG. 3B shows a side view of a cross-section of the cooking pot 32 showing the apparatus 30, where the slot antenna array 37 is mounted on the waveguide 38 and is substantially disposed at the center of the chamber 35. Thus, the RF signal transmitted from the slot antenna array 37 is incident substantially orthogonally to the area of the contour 36 disposed on the side of the chamber 35 of the cooking pot 32. In this particular configuration, the waveguide 38 is used as a feed mechanism for the antenna 39 disposed at the end of the waveguide 38. The antenna 39 provides additional gain to the RF signals transmitted and reflected by the antenna 39. Additionally, the antenna 39 may transmit an RF signal that is substantially orthogonal to the area of the contour 36 disposed at the bottom of the chamber 35 of the cooking pot 32. Desirably, the antenna 39 has a pyramidal horn antenna as described above in the case of the apparatus 10 with reference to FIGS. 1A to 1C. Those skilled in the art will recognize that different types of antennas other than horn antennas, and / or antennas with or without smooth rolled edges, may be used in the apparatus 30. More specifically, a horn antenna having four flare plates, a non-pyramidal horn antenna such as a conical type, or a horn antenna having a non-rectangular cross-section such as an elliptical shape may be used.

[0052] Referring to FIG. 3C, a side view of a cross-section of the cooking pot 32 showing the apparatus 30 is shown, where the first slot antenna 37a, the second slot antenna 37b, and the third slot antenna 37c are respectively mounted on the waveguides 38a, 38b, 38c. The waveguides 38a, 38b, 38c are substantially disposed at the center of the chamber 35. Thus, the RF signals transmitted by the slot antenna arrays 37a, 37b, 37c are incident substantially orthogonally to the area of the contour 36 disposed on the side of the chamber 35 of the cooking pot 32. Desirably, at least one of the waveguides 38a, 38b, 38c is a waveguide having an open end so that it can further transmit an RF signal that is substantially orthogonal to the area of the contour 36 disposed at the bottom of the chamber 35 of the cooking pot 32. More desirably, at least one of the waveguides 38a, 38b, 38c terminates at an antenna.

[0053] Each antenna in the various embodiments shown above can operate with an elliptical polarization generally including linear polarization or generally circular polarization. Further, one or more antennas may operate in a transmit-only mode, and one or more different antennas may operate in a receive-only mode, so that the system operates in a bistatic or multistatic configuration. Alternatively, multiple antennas may operate in a transmit-only mode, a receive-only mode, or a transmit-receive mode, so that the system operates in a multiple-input multiple-output (MIMO) configuration. Further, the transmission of the corresponding signals from the antennas may be performed simultaneously, at different timings, or using an electronic scanning mechanism. Further, each of these antennas may include one or more materials with variable conductivity, RF absorbing materials, metamaterials, ferromagnetic materials, or any combination thereof, configured to improve the performance of at least one antenna or to reduce the electromagnetic coupling between at least one antenna and other antennas or components of a structure that supports or forms part of or is within the furnace.

[0054] Similarly, one or more signal processing methods in the frequency and / or time domain may be used to determine the surface topology of the inner wall and / or bottom of the refractory material within the chamber furnace. In particular, two-dimensional and three-dimensional images of the evaluation results of the material state may be generated from the collected data using one or more signal processing methods including backprojection, delay sum, synthetic aperture radar imaging, backpropagation, inverse scattering, and super-resolution. Further, the application of signal processing techniques is not limited to, but may include, characteristics such as the electromagnetic field, current, electromagnetic radiation gain, input impedance, and polarization of any of the above antennas, and may be used to calculate these characteristic values and support or guide the measurement preparation and data collection process.

[0055] The above configuration is described and used in exemplary embodiments herein, and the terms used are to be understood as non-limiting and terms for explanation. Any configuration disclosed herein may include one or more aspects of other configurations. Exemplary embodiments described herein may be described to explain any principles of the present invention so that those skilled in the art can implement the present invention.

[0056] [Method] A method for evaluating the state of a material according to a further aspect of an embodiment of the present invention is described. The method is carried out to measure at least one RF signal using a transceiver and at least one antenna, wherein the at least one antenna is suitably arranged to transmit and / or receive an RF signal incident on and / or reflected from a predetermined area of the material to be evaluated.

[0057] 1. In step 110, at least one antenna is arranged such that an RF signal can be transmitted and received over a certain frequency band to and from an area surrounding the antenna so that the RF signal is incident on and reflected from a predetermined area of interest of the material to be evaluated. In particular, for a furnace or a cooking pot, the at least one antenna is preferably mounted on the inner wall or permanently embedded in a refractory material surrounding the chamber of the furnace or cooking pot such that the RF signal is transmitted to the area of interest of the inner wall and / or the bottom of the chamber. Alternatively, the at least one antenna may be installed in a structure that may be inserted inside the chamber of the cooking pot or furnace. Preferably, a plurality of antennas are suitably arranged to perform a more accurate and efficient evaluation of a larger portion of a predetermined area of interest in the material to be evaluated.

[0058] 2. In step 120, as described in step 110, it includes transmitting at least one RF signal and using a transmitter and at least one antenna, so that at least one RF signal is incident on the region of interest of the material under evaluation. In particular, for a cooking pot, at least one RF signal should be transmitted into the inner wall and / or bottom of the cooking pot chamber. Desirably, a plurality of RF signals are transmitted using a plurality of antennas.

[0059] 3. In step 130, after at least one transmitted RF signal is incident on the region of interest of the material under evaluation, it includes receiving at least one RF signal and using a receiver and at least one antenna, as described in step 110. Alternatively, at least one RF signal is transmitted by a first antenna and received by a second antenna. In particular, for a cooking pot, at least one RF signal should be incident on the inner wall and / or bottom of the cooking pot chamber. Desirably, a plurality of RF signals are received using a plurality of antennas.

[0060] 4. In step 140, it includes measuring the amplitude and phase of at least one received RF signal after it is incident on the region of interest of the material under evaluation. This may correspond to measuring the scattering parameters S11 and / or S22 of the RF signal reflected and received from the region of interest of the material under evaluation. Alternatively, this may correspond to measuring the S12 and / or S21 scattering parameters related to the RF signal transmitted by a first antenna and received by a second antenna after it is incident on the region of interest of the material under evaluation.

[0061] 5. Subsequently, in step 150, as described in step 140, it includes recording the measured amplitude and phase (S11, S22, S12, and / or S21 scattering parameters) of at least one received RF signal after it is incident on the region of interest of the material under evaluation in a storage device.

[0062] 6. Subsequently, in step 160, if applicable, for multiple positions of at least one transmitting and receiving antenna, or alternatively, for at least one transmitting antenna and at least one receiving antenna, repeating steps 110 to 150 is included, completing the evaluation of a predefined region of interest of the material under evaluation. In particular, for a crucible, the multiple positions of at least one antenna enable the evaluation of the state of the material having the inner wall and / or bottom of the crucible chamber.

[0063] 7. Subsequently, in step 170, if applicable, including resurrecting at least one antenna.

[0064] 8. Subsequently, in step 180, including transferring the collected data to a computer-type processor.

[0065] 9. Subsequently, in step 190, including processing the collected data by at least one signal processing method. Desirably, the signal processing method is selected according to the characteristics of the material under evaluation, such as the dimensions of the material, the type of antenna used, the specific position of the antenna, or the type of material such as molten material in contact with the material under evaluation, regarding the thickness, number of layers, type, and operating frequency band.

[0066] 10. Finally, in step 200, including determining the state of the material under evaluation based on the processed data.

[0067] When the evaluation of the material including the processing of the collected data is completed, the state of the material can be determined. The state of the material may include the level or rate of degradation of the material due to various factors, including thickness, erosion profile, operating wear, operating time, defects, cracks, presence of erosion, and the level or rate of entry of other materials into the material under evaluation.

[0068] The method may further include reducing electromagnetic coupling between at least one antenna and another antenna, or a component of a structure that supports at least one antenna, or a component of a structure that forms part of a furnace, or a component of a structure within a furnace. Additionally, one skilled in the art will recognize that the steps described above may be correspondingly adjusted for a particular evaluation of materials or a particular type of material under evaluation. In particular, the type of data collected may vary in the measurement of S12 or S21 parameters, and / or S11 and S22 parameters, and more specifically, in the techniques used to process the collected data.

[0069] The method and apparatus for the evaluation of the state of a material are disclosed and used herein in exemplary embodiments, and the terms used are to be understood as being used for purposes of illustration and not limitation. One skilled in the art will recognize, with reference to the above teachings, that various modifications and variations of the present invention are possible. It is clear that various modifications and variations of the present invention are possible with reference to the above teachings. The present invention may be practiced by things different from those specifically described within the scope of the appended claims and their legal equivalents.

Claims

1. An apparatus for evaluating the state of a refractory material forming part of a furnace, wherein the furnace contains a molten material different from the refractory material, the apparatus comprising: at least one first antenna physically configured to reduce multiple reflections and probe ringing of a high-frequency signal transmitted or received, the reduction being to a sufficient extent to enable detection of a scattered high-frequency signal after the transmitted high-frequency signal has been scattered from a distant discontinuity of the refractory material, the at least one first antenna being physically configured and arranged such that the transmitted high-frequency signal reaches a minimum to an external structure disposed outside the furnace, the external structure at least partially surrounding the refractory material and inhibiting propagation of the transmitted high-frequency signal through the external structure, the at least one first antenna being embedded in a portion of the refractory material and disposed between the external structure and the molten material, and being adapted to enable reception of the scattered high-frequency signal from the distant discontinuity of the refractory material within a sufficient time to distinguish the scattered high-frequency signal from spurious signals reflected from other discontinuities; a transceiver capable of generating the high-frequency signal transmitted by the at least one first antenna, capable of detecting the high-frequency signal received by the at least one first antenna, and being electromagnetically coupled to the at least one first antenna; a first computer-type processor having a data storage device and executable computer code configured to measure the scattered high-frequency signal received to generate time-domain data or frequency-domain data converted to time-domain data, calibrate the time-domain data to distance-domain data, identify peaks in amplitude in a distance-domain profile related to the distant discontinuity of the refractory material, and determine the distance traveled by the received scattered high-frequency signal; a connection channel enabling connection of the at least one first antenna to at least one of the transceiver and the first computer-type processor, having at least one element selected from the group consisting of transmission lines, communication lines, control lines, and power lines, and being constituted by at least one of a set of cables and wireless; the apparatus.

2. The at least one first antenna has a pyramidal horn antenna having a rectangular cross-section, and has a first flare plate and a second flare plate arranged to face the first flare plate. The first flare plate has a planar portion and two flare portions along opposing side edges of the planar portion of the first flare plate. The apparatus according to claim 1, wherein the second flare plate has a planar portion and two flare portions along opposing side edges of the planar portion of the second flare plate.

3. The apparatus according to claim 2, wherein the thickness of at least one of the first flare plate and the second flare plate is changeable.

4. The apparatus according to claim 2, wherein the ratio of the thickness to the length of at least one of the first flare plate and the second flare plate is in the range of 15% to 85%.

5. At least a part of the volume region between the first flare plate and the second flare plate has an insulator material. The apparatus according to claim 2, wherein the insulator material extends beyond the two flare portions along opposing side edges of the at least one planar portion of at least one of the first flare plate and the second flare plate.

6. The apparatus according to claim 1, wherein the at least one first antenna operates while being embedded in the refractory material and is designed and physically configured to be essentially impedance-matched to the refractory material.

7. The apparatus according to claim 1, wherein the at least one first antenna is embedded in at least one forged portion of the refractory material.

8. The apparatus according to claim 1, wherein at least a part of at least one of the transceiver and the first computer-type processor is embedded in the refractory material.

9. The external structure at least partially surrounding the refractory material has elements selected from the group having a shell formed of a conductive material forming part of the furnace, a lattice structure providing additional mechanical support to the furnace, and a structure arranged near the furnace. The apparatus according to claim 1.

10. The apparatus according to claim 1, wherein the state of the refractory material to be evaluated is an element selected from the group having the thickness of the refractory material, the defects of the refractory material, and the level of entry of the molten material into the refractory material.

11. The apparatus according to claim 1, wherein the at least one first antenna is arranged according to at least one element selected from the group having the antenna radiation pattern of the at least one first antenna, the electromagnetic coupling effect and possible interference between the at least one first antenna and other elements surrounding the at least one first antenna, the position of the external structure, and the region of interest of the refractory material under evaluation.

12. Having a plurality of antennas arranged in a set of a plurality of antennas, Each set of the set of the plurality of antennas is controlled by a second computer-type processor, The apparatus according to claim 1, wherein the second computer-type processor is controlled by the first computer-type processor.

13. The apparatus according to claim 1, wherein the first computer-type processor is configured to enable the implementation of at least one signal processing method in at least one of the time domain and the frequency domain so as to process a set of data for the determination and visualization of the state of the refractory material and the prediction of the remaining operating life and maintenance plan of the furnace.

14. The refractory material and the external structure have a physical configuration that enables routing of the connection channel, The apparatus according to claim 1, wherein the physical configuration includes grooves, holes, recesses, cuts, ducts, and passages.

15. The apparatus according to claim 1, wherein the connection channel has at least one cable capable of withstanding a high temperature of at least 500 °C.

16. Further comprising at least one second antenna disposed in a chamber of the furnace in which the molten material is processed, The at least one second antenna is disposed at a position selected from the group having a substantially central position of the chamber, a position offset from the center of the chamber, and a position adjacent to the inner wall of the refractory material. The apparatus according to claim 1, wherein the executable computer code is executed when the furnace is not operating or is completely or partially empty.

17. A method for evaluating the state of a refractory material forming part of a furnace, comprising At least one first antenna physically configured to reduce multiple reflections and probing of high-frequency signals transmitted or received, the reduction being to such an extent as to enable detection of scattered high-frequency signals after the transmitted high-frequency signal is scattered from a distant discontinuity of the refractory material, the at least one first antenna being physically configured and arranged such that the transmitted high-frequency signal minimally reaches an external structure disposed outside the furnace, the external structure at least partially surrounding the refractory material and inhibiting propagation of the transmitted high-frequency signal through the external structure, the at least one first antenna being embedded in a portion of the refractory material and disposed between the external structure and the molten material, and being adapted to enable reception of the scattered high-frequency signal from the distant discontinuity of the refractory material within a sufficient time to be able to distinguish the scattered high-frequency signal from spurious signals reflected from other discontinuities, to provide at least one first antenna. Arranging the at least one first antenna according to at least one element selected from the group consisting of the antenna radiation pattern of the at least one first antenna, the electromagnetic coupling effect and possible interference between the at least one first antenna and other elements surrounding the at least one first antenna, the position of the external structure, and the region of interest of the refractory material under evaluation, such that the transmitted high-frequency signal is incident on a predetermined region of interest of the refractory material under evaluation and the received scattered high-frequency signal is scattered from the predetermined region of interest of the refractory material under evaluation. Transmitting at least one high-frequency signal using a transmitter and the at least one first antenna such that at least one transmitted high-frequency signal is incident on the region of interest of the refractory material under evaluation. Detecting at least one high-frequency signal using a receiver and the at least one first antenna after the at least one transmitted high-frequency signal is incident on the region of interest and scattered from a distant discontinuity of the refractory material under evaluation. Determining the state of the refractory material based on a determined distance traveled by the detected high-frequency signal scattered from the distant discontinuity of the refractory material under evaluation. A method comprising. Claim 18 Measure and record a set of data regarding at least one of the detected high-frequency signals so as to generate recording data. If applicable, convert the recording data into time-domain data. Calibrate the time-domain data with distance-domain data. Identify peaks in the distance-domain data related to the detected high-frequency signals scattered from the remote discontinuities of the refractory material under evaluation. Determine the distance traveled by the detected high-frequency signals scattered from the remote discontinuities of the refractory material under evaluation. Based on the determined distance traveled by the detected high-frequency signals scattered from the remote discontinuities, the properties of the refractory, the properties and arrangement of the at least one first antenna, and at least one signal processing method selected according to the type of molten material in contact with the refractory material under evaluation, determine the state of the material. The method according to claim 17, further comprising the above.

19. The method according to claim 17, wherein the at least one first antenna is embedded in at least one forged portion of the refractory material.

20. The method according to claim 17, wherein the external structure at least partially surrounding the refractory material has elements selected from the group having a shell formed of a conductive material forming part of the furnace, a lattice structure providing additional mechanical support to the furnace, and a structure arranged near the furnace.

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