Numerical simulation of dust control technology for longwall working face with convective air curtain

A convection-type air curtain dust control system and method were proposed to effectively control the high dust concentrations generated during the operation of coal miners and hydraulic supports and to reduce the dust concentration in the entire working space of longwall work surfaces, and the effectiveness of air curtain dust control during single process operation was investigated through numerical simulation. The results showed that when the miner was working alone, there was a significant difference in the concentration distribution inside and outside the dust-proof air curtain, with significantly lower dust concentrations in the area where the miner drivers were operating compared to both sides, with an average dust mass concentration of around 420 mg/m3. Dust concentrations increased to about 700 mg/m3, but large amounts of dust were prevented from diffusing downwind. This indicates that the dust reduction effect is more pronounced after the equipment is opened, which can improve the working environment and reduce the probability of dust combustion and explosion accidents.

The impacts of the axial-to-radial airflow quantity ratio and suction distance on air curtain dust control in a fully mechanized coal face

To understand the impacts of the axial-to-radial airflow quantity ratio (denoted as R) and the suction distance (denoted as D_s) on air curtain dust control in a fully mechanized coal face, the 3_down610 coal face in Jiangzhuang coal mine was numerically simulated in this study. A mathematic model was established to describe the airflow migration and dust diffusion in a coal face, and a scaled physical model was constructed. The comparison between simulation results and field measurements validated the model and the parameter settings. Furthermore, the airflow migration and dust diffusion at various R and D_s are analyzed using Ansys CFD. The results show that a reduction of R and D_s is conducive to the formation of an effective axial dust control air curtain; the dust diffusion distance decreases with the decrease of both R and D_s. By analyzing the simulation results, the optimal parameter for air curtain dust control in the 3_down610 coal face and those faces with similar production conditions is determined as R = 1/9 and D_s = 2 m. Under the optimal parameter condition, the high-concentration dust can be confined in front of the mining driver within a space 5.8 m away from the coal face.