Transient three-dimensional modelling of industrial-scale ironmaking blast furnaces and applications to sustainable and low-carbon ironmaking

The core contribution of this thesis is the development of a new generation three-dimensional (3D) transient blast furnace model based on a previously developed two-dimensional (2D) transient CFD model. Earlier CFD blast furnace models were either 2D or steady-state, and thus could not capture both temporal and spatial characteristics simultaneously. This capability is important because blast furnace operations often face non-uniform conditions or adjustments in operating parameters. Non-uniform conditions require a 3D model to capture spatial variations, while changes in operating conditions cause the furnace state to evolve over time, which calls for a transient model to track temporal changes. In particular, when operating conditions change from uniform to non-uniform, a 3D transient model is necessary to capture variations in both space and time. The model is the world’s first to achieve this. After developing the model, industrial blast furnace operating data were integrated and the results were compared with actual production data. The comparison showed that our model produces results close to operation data measured, demonstrating its reliability. The model was then used to study how internal furnace phenomena change as blast temperature becomes non-uniform. This case study confirmed the effectiveness of the model. To support industry efforts in blast furnace decarbonisation, the effects of hydrogen injection and Hot Briquetted Iron (HBI) charging on furnace performance were studied. For hydrogen injection, two schemes were analysed: one that starts injecting hydrogen through some of the tuyeres and gradually expands to all, and another where all tuyeres inject hydrogen from the start but the injection amount increases over time. Taking advantage of the transient model, hydrogen flow paths, local chemical reactions, and temperature changes over time are captured. In the HBI study, different charging strategies were studied using a steady-state model. The results showed that even with the same quantity of HBI, different charging methods lead to distinct internal furnace phenomena. Overall, these decarbonisation strategies reduce coke rate, thereby lowering carbon emissions. This model will be further developed to study a wider range of renewable and sustainable ironmaking operations.