DEM-CFD Coupling Simulation of Acid Gas Entrainment and Corrosion in Industrial Activated Carbon Regeneration Towers: Flow Velocity Effects and Mechanisms

Abstract In response to the severe corrosion of the regeneration tower in the activated carbon desulfurization and denitrification system for industrial coke oven flue gas, this study employed a coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) numerical simulation approach. Through steady-state simulations, the gas–solid two-phase flow characteristics and the migration and distribution patterns of acid gas within the regeneration tower are systematically analyzed. The results show that at low-velocity (0.3 m/s), the axial cross-section is dominated by low-velocity zones, and stagnant regions readily form between particles, inducing local accumulation of acid gas. At medium-velocity (0.5 m/s), the flow field in the axial cross-section transitions smoothly, the terminal velocity of the acid gas matches the flow field well, and the gas flow remains stable with the lowest residual risk. At high-velocity (0.8 m/s), turbulence-induced jet effects are pronounced in the axial cross-section, leading to significant acid gas entrainment. On this basis, the synergistic corrosion mechanism involving chemical corrosion and particle erosion within the tower is further revealed. This study provides critical theoretical insights for optimizing operational parameters and implementing corrosion prevention strategies in activated carbon regeneration towers.