An Integrated Optimal Control Model for the Drying and Preheating Process in Iron Ore Pellet Manufacturing

The drying and preheating process plays a crucial role in the induration of iron ore pellets. It is conducted on a closed, moving bed in both the straight grate and grate-kiln processes. The internal state of the pellet bed cannot be measured and the manipulated parameters are set according to the experience. An integrated optimal control model based on the numerical simulation and intelligent algorithm is proposed. In this model, the moisture content and temperature of pellets in each stage are predicted via the mathematical simulation, and the inlet gas temperature is optimally set and real-time controlled through the multi-objective optimisation and Takagi–Sugeno fuzzy control methods. The proposed model has been successfully applied to a large-scale pelletising plant. The closed-loop running results illustrate that the thermal state of the pellet bed becomes stable, and the pellet production is improved while the mixed gas consumption is reduced.