A model for burden distribution and gas flow distribution of bell-less top blast furnace with parallel hoppers

摘要

In the present work, a collision model is established and combined with a hydrodynamic model, 3D collision trajectory, Coriolis force model and drag force model to build a hybrid model for predicting the position of the pile surface in a blast furnace with parallel type hoppers. The described model is then validated by test data and scene photos of the worn chute. According to this model, different gas flow profiles are formed at different development stages after the burden distribution is finished. During the "initial stage" which accounts for 30% of the total time of gas flow development, the development of gas flow is mainly influenced by the burden surface of ore. During the "intermediate stage" which accounts for 40% of the total time, the development of gas flow is influenced by both the burden surface of ore and the burden surface of coke. During the "late stage" which accounts for 30% of the total time, the development of gas flow is mainly influenced by the burden surface of coke. The "snakelike" segregation in the burden surface of blast furnace with parallel hoppers is caused by the variation in Coriolis force on the burden flow at the chute exit during one revolution of the chute (the range in total Coriolis acceleration for chute inclination angle of 42.5° is 1.36-3.01 m/s~2 for ore and 0.36-4.40 m/s~2 for coke). The model can provide real time guidance for burden distribution in a blast furnace. The segregation in the burden surface can be reduced by adding a center discharge valve.