Transient thermal behavior of a steel-strip loaded into a continuous annealing furnace with SiC electric heaters

초록

Electrification of continuous annealing furnaces is a crucial step toward achieving zero-carbon emissions and improving the thermal efficiency of galvanizing lines. This study evaluated the feasibility of an electrically heated continuous furnace and investigated the transient thermal behavior of a steel-strip. The furnace employs SiC heating elements to achieve temperatures exceeding 1250 ℃. Experimental data and 3-D transient computational fluid dynamics (CFD) simulations were used to validate the model and analyze thermal behavior. The physical properties of SiC were incorporated into the model across a temperature range of 20–1600 ℃, yielding results that closely aligned with the heater manufacturer's design specifications. Additionally, the emissivity of the steel-strip was implemented as a temperature-dependent function, and the experimentally measured power input was integrated into the model. A transient steel-strip temperature profile was obtained, demonstrating strong agreement with the experimental data. Moreover, a well-validated CFD model was established for the electrically heated continuous steel-strip annealing furnace. The results revealed an inverse relationship between the strip speed and temperatures of the furnace interior, inner wall, and steel-strip. This is attributed to variations in the residence time, where lower strip speeds allow for longer heat exposure, enhancing the radiative heat transfer and reducing the temperature gradient across the strip width. Initially, the heating rate at the strip edges was higher than that at the center because of the localized radiative heat flux. However, this trend reversed as the strip progressed, leading to improved temperature uniformity. These findings provide valuable insights for scaling up electrically heated continuous annealing furnaces and demonstrate the feasibility of a heating system with zero carbon emissions. © 2025 Elsevier Ltd

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