A Computational Fluid Dynamics Simulation Method to Optimize the Structure Parameters of Coal-Based Flash Ironmaking Reactors

The coal-based flash ironmaking furnace is designed to industrialize the novel flash ironmaking technology (FIT), which is recognized as a cleaner and efficient alternative ironmaking process. To realize gas-particle contact, researchers use the cocurrent downer to reduce bonding, and the reactor structure has a significant effect on the flow pattern. Herein, a 3D computational fluid dynamics (CFD) model is developed to obtain an in-depth understanding of the geometry parameters, including ore feeding position (r/R), shaft diameter (D), and height-to-diameter ratio (L/D). The simulation results show that the secondary gas flow caused by the dropping hematite particles might enhance or destroy the primary turbulence structure when r/R was below or above 0.6. The increased shaft diameter D expanded the recirculation zone, which helps to prolong the residence time and improve the species exchange. The particles' reduction degrees first rise and then fell, and the highest value (90.89%) is attained at D = 2.2 m. On the contrary, the increased L/D ratio does not change the turbulence structure but prolongs the length of the plug zone. It also shows a positive but declining effect on the reduction degree from 89.7% to 99.8%.