Mathematical Modeling of the Prereduction Process of Iron Ore in a Circulating Fluidized Bed

Abstract

AbstractA mathematical model has been developed to describe the various subprocesses occurring in a circulating fluidized bed (CFB) used for pre‐reduction of iron ore particles in the smelting reduction iron‐making process. The model incorporates hydrodynamics, iron reduction kinetics, and heat and mass transfer. One of the key features is the inclusion of a wall‐to‐bed heat transfer model to describe the heat transfer phenomena occurring in the CFB. The predicted and measured heat transfer coefficients showed a minima in the lower part of the bed due to the irregular up‐and‐down movement of ore particles. The model predictions of the reduction degree of iron oxides based on shrinking‐unreacted‐core chemical reaction control mode showed satisfactory overall agreement with measured data. The performance of the CFB reactor has been tested extensively in terms of gas oxidation degree, inlet temperature, particle size and mean particle residence time. It was confirmed that the reduction degree is significantly affected by gas oxidation degree, wall temperature and particle size.