Mathematical model for predictive control of the bell-less top charging system of a blast furnace

Modern blast furnaces use bell-less top systems for the charging of the solid feed into the furnace. The complete potential of the charging system for distributing the material in the furnace cross-section in any desired profile can be achieved only by using a suitable charge distribution model. By considering the flow of different types of solid particles like iron ore, sinter and coke through the bin and rotating chute, equations have been developed for the particle trajectories. The formation of the ring shaped hill of material by the accumulation of the falling material has been modeled considering the angle of repose, rolling and layer penetration. These relationships have been combined with appropriate corrections for the burden descent and the mixed layer formation to develop the overall geometry of the stock line. The burden charge model has been used in an optimization routine to determine the best charging pattern to transit from an existing stock line geometry to a new geometry. The models have been tested in an operating furnace and incorporated in a supervisory control system.