CFD-FEA modelling of tuyere damage in an industrial ironmaking blast furnace: A case of coke oven gas injection

• A CFD–FEA model was built to analyse thermal stress in a blast furnace tuyere during COG injection. • Critical stress (>2.0 GPa) occurred at tuyere tip edges, where temperatures rose above 1900 K. • Stress fluctuations (2.0–2.8 GPa, ±100 MPa) near the blowpipe and cooling chamber indicate fatigue risk. • An Fe–Cr coating kept the tuyere core below 780 K and reduced average thermal stress by 41%. Tuyere damage is a recurring issue in ironmaking blast furnaces (BFs), and frequent failures may lead to significant operational disruptions. However, the thermal stress contributing to such damage remains insufficiently understood, particularly in the emerging operation of coke oven gas (COG) injection. In this study, an industrial-scale tuyere-raceway model is developed by combining Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) and used to analyse the thermal stress during COG injection. The results show that thermal stress peaks at the outer edges of the tuyere tip, where the temperatures exceed 1900 K and thermal stresses surpass 2.0 GPa. Additionally, unlike other regions of the tuyere, the blowpipe and the areas adjacent to the cooling chambers exhibit temporal fluctuations in thermal stress, with stress levels ranging between 2.0 and 2.8 GPa and fluctuations of approximately 100 MPa, which may increase the risk of fatigue and crack propagation. As a countermeasure, the application of an Fe-Cr coating is tested and can effectively insulate the tuyere core, maintaining its temperature below 780 K and reducing the average thermal stress on the tuyere core surface by 41% compared to uncoated designs. The CFD-FEA integration model offers a cost-effective tool for optimising tuyere design and operating parameters under new BF conditions.