A UDS-Based Pseudo-Fluid Moving-Bed Dual-Temperature CFD Framework for Hydrogen-Rich Shaft Furnaces Using Coke Oven Gas

Hydrogen-rich shaft furnaces operated with coke oven gas (COG) represent an important low-carbon ironmaking route. Conventional porous-medium CFD models, however, do not explicitly resolve geometry-dependent burden descent or downward advection of solid sensible heat in variable-cross-section moving beds. To address this gap, a user-defined-scalar (UDS)-based pseudo-fluid moving-bed dual-temperature CFD framework is developed in this study. The framework couples geometry-dependent pseudo-solid kinematics, UDS-based transport of pseudo-solid species and sensible enthalpy, and a 12-step reduction-reforming-carbon reaction network on a fixed Eulerian mesh. It is applied to a 0.5 Mt·a−1 industrial reactor through one reference case and three parametric groups covering solid descent velocity, cooling-side back pressure, and CH4 content. Mesh-independence and mass-conservation checks indicate that the medium mesh is adequate for the intended trend-level assessment; the fine-to-medium deviations are 0.54% for DRI metallization, 0.23% for DRI outlet temperature, and 0.20% for top-gas temperature, with a net global mass residual of 1.53 × 10−6 kg·s−1; the baseline DRI metallization (96.3%), carbon content (1.1%), and combined H2 + CO utilization (29.45%) all fall within the reported ranges of the HBIS demonstration line and Energiron-ZR projects. As the descent velocity increases from 2.88 to 6.72 × 10−4 m·s−1, DRI metallization drops from 98.0% to 79.4% and the outlet temperature rises from 313.3 to 719.4 K. Increasing the cooling-gas outlet back pressure from 60 to 100 kPa reduces the cooling-outlet excess flow from 1.49 to 0.11 kg·s−1, indicating a dynamic gas-seal control between the two gas circuits, whereas raising the inlet CH4 fraction from 10 to 23 vol% lowers the apparent CH4 conversion from 29.5% to 18.5% and broadens the carbon-deposition zone. The framework offers a continuum basis for proof-of-concept and trend-level analysis of variable-cross-section hydrogen-rich moving-bed shaft furnaces.