Distributed Temperature Sensing in the Spray-Cooled Shell of a 150-Ton DC Electric Arc Furnace Using Brillouin Optical Fiber Technology

This paper presents the deployment and validation of a Brillouin - distributed temperature sensing (DTS) system for real-time thermal monitoring of the spray-cooled upper shell of a 150-ton direct current Electric Arc Furnace (DC EAF) at Big River Steel Plant, Osceola, AR, USA. A four-channel Brillouin DTS system from OZ Optics was employed, with one active channel instrumented using an in-house-fabricated Brillouin scattering-depressed single-mode optical fiber (SMF28e+). The 60 m optical fiber sensor was fabricated, with 20 m allocated for thermal measurement and 40 m used as lead-in fiber to isolate the interrogator from the furnace environment. The fiber was nested in stainless steel (SS) tubing and bonded to the hot-face surface of the shell using thermally conductive epoxy. The system captured transient thermal events including burner activation and process-induced heating over multiple furnace cycles. DTS-acquired data were validated against resistance temperature detector (RTD) measurements, confirming consistent thermal trends and system accuracy. Prior to the industrial deployment, several mock-up tests were conducted. Laboratory calibration demonstrated a linear Brillouin frequency shift with temperature, with a sensitivity of approximately 1.19 °C/MHz up to 515 °C and R2= 0.9988. Additional mock-up trials confirmed spatial resolution between 0.5 m and 1 m, with transmission and reflection spectra showing hotspot detection over sensing lengths up to 130 m. An averaging spatial step of 0.04 m was used, and acquisition sweep time was set to 1 min with a 10 MHz frequency step size and 10,000 averages. Monitoring the spray-cooled shell is critical in EAF operations due to its exposure to high thermal loads and susceptibility to localized overheating. Real-time hotspot detection and localization support proactive maintenance, reduce the risk of shell failure, and improve energy efficiency and operational safety. These findings underscore the potential of Brillouin - DTS systems to enable intelligent process control and predictive maintenance in next-generation steelmaking facilities.