A Mathematical Model for Straight-Grate Iron Oxide Pellet Induration Furnace: Formulation, Plant Scale Validation, Implementation and Control

In this work, a mathematical model for the straight-grate pellet induration furnace is presented. The induration furnace is an equipment used for the efficient heat and mass transfer between the pellet bed and the flowing gas. The model includes different physicochemical phenomenon like gas-solid heat and mass transfer, drying and condensation of free surface moisture, combustion of carbon, calcination of limestone and kinetics of loss of ignition (LOI) removal from hydrated iron ore. The model is validated with the experimental and numerical data available in the literature. For the first time, an extended validation of the model against the plant scale ThermoCar (T-CAR) test is also presented. The developed model is implemented at AM/NS India pellet plants including the model assisted control to the online furnace operation. The effect of change in different furnace operating parameters on the thermal and chemical state of the pellet bed inside the furnace can be easily evaluated from the model results. The model can be used as an offline tool for optimizing the furnace parameters, increasing plant productivity, improving fired pellet properties, pilot run of new product mix, operator training purpose and as an online visualization tool for the better operational control and stability.