(359b) 3D Transient CFD Modeling of a Novel H2-DRI Shaft Furnace

Steel production contributes over 7% of global CO₂ emissions, mainly due to fossil-fuel reliance in conventional furnaces. In contrast, Direct-reduced iron (DRI) shaft furnaces using hydrogen-based reducing gases offer a cleaner alternative. This work introduces a novel process that employs turquoise hydrogen and solid carbon from methane pyrolysis for DRI furnace operation.

CFD modeling is used here to explore the complex moving-bed hydrodynamics and multiphase reactive flow within the furnace. While most existing studies rely on 2D steady-state models, our study employs a 3D transient multiphase reacting flow solver based on the MP-PIC methodology, which efficiently tracks both Lagrangian and Eulerian phases. Validated against MIDREX furnace modeling results (Hamadeh 2018), our model incorporates state of the art kinetics from literature relevant to the process of DRI production. Unlike the vast majority of literature which lumps both iron carbide and carbon into a single species, we model the production of these both as distinct reactions (adapted from Mondal 2004). Coupling these kinetics with the high-efficiency MP-PIC algorithm enables this model to be used as a tool in investigating key reactor operating conditions that impact the operation of a DRI shaft furnace.

Building on our validated MIDREX CFD model, the next steps involve adapting the model for H₂-DRI operation. In this approach, carbon-containing species in the inlet cooling section are replaced with an inert gas, and a hydrogen-rich pyrolysis gas from Molten’s patented process is used as the reducing agent. Initial modeling results indicate a dramatic reduction in CO₂ and other greenhouse gas emissions, with minimal impact on the moving-bed hydrodynamics and iron yields comparable to those of the MIDREX furnace. Analysis of the temperature profile of the vessel has shown that the cooling gas can adequately replace the cooling gas feed with little impact on the temperature profile in either the cooling section or reducing section of the furnace. Modeling has also demonstrated a more rapid conversion of metal oxide species associated with usage of the pyrolysis gas as a reducing agent. Further modeling efforts are focused on optimizing the temperature of the introduced pyrolysis gas and evaluating carbon utilization, with the presentation set to highlight key performance comparisons between the H₂-DRI and MIDREX systems.