Optimization of spray dust suppression device in return air tunnel of a coal mine based on CFD technology

A wet and dry dual-purpose dust reduction device was developed to reduce the level of harm caused to mineworkers by the respirable dust generated in a fully mechanized working face in a coal mine, and specifically those workers located in the return airway [1]. First, spraying experiments were carried out to generate data showing an efficient dust reduction effect. Then, the data obtained from the experiments were imported into computational fluid dynamics (CFD) software for the numerical simulation of spraying [2]. The influence of the outward extension distance of the nozzle ( Ls ) and the spraying pressure ( Pw ) on the coverage capacity of the dust capture mesh and the distribution of the spray field was determined. According to the experiments, the optimal nozzles were 2.4-mm round-orifice nozzles with X-shaped flow guide cores. When Ls = 25 cm and Pw = 7 MPa, the spray field covered the dust capture mesh to the greatest degree, and effective dust reduction was achieved. Field application and measurements were carried out in the return airway of the 117 fully mechanized working face of Jinjitan Coal Mine, China. The dust reduction efficiency was found to reach 90.25%. Following the reduction in dust, the concentrations of respirable dust in the return airway at distances of 20, 50, and 80 m from the fully mechanized working face were 0.250, 0.203, and 0.179 mg/m 3 , respectively. As a result, the dust pollution problem in the return airway was effectively solved, and the airway environment was significantly improved. • Developed a combined dry and wet dust suppression device for the return air tunnel. • We optimized nozzles selection and verified numerical simulation. • We obtained distribution law of spraying field and best spray parameters. • The device can effectively settle the respirable dust in air return roadways.