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This study introduces an innovative approach to enhance safety in electric arc furnaces (EAFs) through the integration of optical fiber sensors (OFS) in the refractory lining bricks’ assembly. By demonstrating the significant benefits of OFS, we showcase its effectiveness in continuous thermal monitoring and location profiling within the EAF refractory lining. The work focuses on detecting the onset of water leakage in the vicinity of the burner of an EAF, with thermal data resolution up to 1.3 mm. The instrumented OFS in this work were able to detect volumes of water leaks (from a controlled water drip pipe with flow rates $\ge 2.3$ cc/min) at temperatures $\gt 500~^{\circ }$ C, indicating their potential for promptly identifying and informing maintenance actions. Prompt maintenance actions would help to mitigate catastrophic consequences of water leakages such as steam explosions. Furthermore, proactively addressing water leakage issues can extend furnace lifespan and the overall safety of EAF operations. Therefore, our work aims to enhance safety and minimize downtime and maintenance costs by providing distributed and real-time thermal profiling solutions to the water leakage concerns in the refractory lining bricks’ assembly around the burner of an EAF.

This research reports a distributed fiber optic high-temperature sensing system tailored for applications in the steel industry and various other sectors. Recent advancements in optical sensor technology have led to the exploration of sapphire crystal fibers as a solution for sensing in harsh environments. Utilizing a femtosecond (fs) laser, cascaded fiber Bragg gratings (FBGs) were meticulously fabricated within a multimode sapphire optical fiber. These FBGs endowed the system with distributed sensing capabilities and underwent rigorous testing under extreme temperatures, reaching up to 1800 °C. The study delves into the investigation of the FBG reflection spectrum, facilitated by the development of a sophisticated multimode demodulation system, which contributed to the attainment of precise temperature measurements with a performance accuracy of 99.9%. Demonstrating exceptional thermal stability, the sapphire FBGs endured temperatures of 1600 °C for a sustained duration of 22 h. Furthermore, this article explores the application of distributed temperature sensing employing multiple sapphire FBGs, showcasing their utility in temperature measurements related to molten steel studies.

This study reports the fabrication of a fourth-order line-by-line fiber Bragg grating (FBG) array using femtosecond laser inscription within a highly multimode coreless optical fiber, with a particular focus on achieving substantial multiplexing capabilities. An ultrafast annealing procedure is employed, resulting in an impressive enhancement of the FBG sensor’s fringe visibility by approximately 13 dB, signifying a notable improvement of approximately ~4 dB. This substantial enhancement contributes to the long-term stability and performance of the multiplexed FBG array in extreme-temperature conditions. The systematic fabrication approach employed for the multiplexed FBG array guarantees a high signal-to-noise ratio (SNR) for each individual FBG within the array. This FBG array is intended for extreme-temperature applications, addressing limitations associated with traditional FBGs based on doped optical fibers, including SNR degradation and temperature-induced fringe drift. Testing at temperatures up to 1120 °C demonstrates the FBG array’s stability without fluctuations in readings. Furthermore, it endures seven heat cycles, spanning from 500 °C to 1120 °C, over 60 h, exhibiting outstanding thermal stability. This highly multiplexed FBG array with an ultrafast annealing approach holds promise for extreme-temperature environments, such as steelmaking, where precise and reliable distributed temperature monitoring is imperative.