Impact of Hydrogen Combustion on Thermal Stresses & Scale Formation in a Reheat Furnace

This thesis investigates the use of hydrogen as a cleaner alternative to natural gas in steel reheating furnaces by modeling two industrial setups: the Cleveland-Cliffs Indiana Harbor Furnace, where hydrogen-methane blends were applied across all zones, and the Gerdau Monroe furnace, where hydrogen was limited to the soak zone. Through Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA), the study evaluated the thermal and mechanical behavior of slabs under varying fuel conditions. Results showed that full hydrogen use raised average temperatures by 9.9% in the Cleveland-Cliffs furnace, while partial use in Gerdau’s setup led to a 3% increase. Although hydrogen enabled faster slab heating, it introduced sharper temperature gradients, which in turn elevated average thermal stresses by 1–8%, though peak stresses remained localized at the skid contacts.

Additionally, the study assessed hydrogen’s impact on oxide scale formation using customized user-defined functions integrated into the CFD model. These simulations, validated against experimental data, showed that hydrogen combustion led to 5–15% more scale buildup than methane, with the soaking zone exhibiting the most growth. This excess scaling reduced slab core temperatures by up to 12F, potentially affecting heat transfer efficiency and final product quality.