Computational fluid dynamics study of the structural optimisation for blast furnace bag filters

The blast furnace bag filter is an essential equipment for filtering flue gas and recovering dust. Optimising its structure can enhance gas recovery efficiency, reduce resource waste, and mitigate environmental pollution. This study designed three types of blast furnace metal bag filters with varying inlet and outlet structures and analysed their flow field distribution characteristics using computational fluid dynamics. The results indicated that the airflow was most efficient with the configuration of a lower inlet and upper outlet on the same side (Case A). However, Case A exhibited significant flow fluctuations in the filter bag area and slightly higher wall stress compared to the middle inlet structure (Case B). While the airflow in Case B's filter bag area was relatively uniform, there was strong disturbance at the ash hopper, hindering the efficiency of ash deposition. In addition, Case C, featuring a lower intake on one side and an upper outlet, demonstrated the poorest flow performance. Therefore, Case A was deemed the most scientifically optimal structure for the actual industry. Additionally, the study examined the impact of inlet velocity on flow characteristics in Case A. As the inlet velocity increased from 9.8 to 29 m/s, the flow velocity in the ash hopper area rose from 2.57 to 6.01 m/s, with a marked increase in jet intensity.