Comprehensive Mathematical Model for Particle Flow and Circumferential Burden Distribution in Charging Process of Bell-less Top Blast Furnace with Parallel Hoppers

Parallel hoppers type bell-less top is one kind of widely used charging apparatus, and it is essential to clarify particles flow behavior and circumferential burden distribution during charging process. Thus in this paper, a comprehensive mathematical model from flow control gate to stock surface has been established. In the model, the trajectory shape of particles colliding point on rotating chute with semi-circular section is firstly clarified, not simply an ellipse shape, and the mathematical model of particles flow behavior on rectangular type chute is initiatively presented. The model is then validated by measured results of coke particles falling trajectory in the freeboard using laser grids method during the blow-in stage of an actual 2 500 m(3) blast furnace. Based on the established model, the projected trajectories of particles colliding point on rotating chute are clarified for semi-circular type chute and rectangular type chute respectively, and circumferential variations of particles effective motion length and motion time on the chute are investigated. In addition, circumferential burden falling point distribution and mass flow rate distribution on stock surface are deeply analyzed, and the phenomenon that semi-circular type chute tends to cause larger nonuniformity than rectangular type chute is realized. The model has great significance and application value in predicting and recognizing nonuniform burden distribution in parallel hoppers type blast furnace and further improving blast furnace operation.