Effects of spraying pressure and installation angle of nozzles on atomization characteristics of external spraying system at a fully-mechanized mining face

Aiming to effectively suppress excessively high dust concentration around the drums during coal cutting and the related dust particle dispersion issues at a fully-mechanized mining face, the present study employed experiments, numerical simulations, and field measurements to carry out an in-depth investigation of the dust suppression performance of an external spraying system. Firstly, the atomization characteristics of the nozzles with optimized macro-atomization performances were tested. According to the experimental results, hybrid nozzles with an orifice diameter of 2.0 mm and an X-shaped diversion core (type-B nozzles) delivered the best overall atomization performances at a spraying pressure of 8 MPa; in this case, the spraying angle and the effective spraying range were approximately 81.9 degrees and 2.56 m, respectively. Next, numerical simulations were conducted to assess the dust suppression performances of an external spraying system, using ANSYS Fluent software. The results showed that, when the nozzles were installed at an inclination angle of 30 degrees and operated at a spraying pressure of 8 MPa, the spray field formed could cover the whole dust-producing region around the drum. Meanwhile, the spray field near the coal cutter drum was not affected by airflow, which prevented dust particles being dispersed by the airflow, leading to a mitigation of pollution. Finally, field testing at the No. 30106 mining face of the Shiquan Coal Mine indicated that the mean overall dust suppression efficiency could reach up to 90.10%, i.e. the dust particles at this fully-mechanized mining face were effectively settled. To conclude, the dust pollution issues at a fully-mechanized mining face during the coal cutting process were adequately addressed by the measures investigated here. (C) 2018 Elsevier B.V. All rights reserved.