An investigation of the nozzle's atomization dust suppression rules in a fully-mechanized excavation face based on the airflow-droplet-dust three-phase coupling model

In order to suppress the diffusion of high concentrations of dust towards the operating area in a fully-mechanized excavation face effectively, this study constructed a mathematical model that describes the interactions among droplets, dust and airflows, and then validated the accuracy of the established model. Finally, under single-forced ventilation conditions, the dust suppression rules when different nozzles were used at different spraying pressures were investigated in detail. The results reveal that when different spraying schemes were used, the dust mass distributions in different regions along the tunnel were basically the same; they all first decreased, then increased and finally decreased. At a spraying pressure of 2-8 MPa, the spraying pressure and dust suppression efficiency followed a logarithmic function; however, with an increase in the spraying pressure, the dust suppression efficiency increased gradually at a declining rate. Under a spraying pressure of 8 MPa, the dust clusters in which the dust concentration exceeded 110 mg/m(3) in the fully-mechanized excavation face were reduced significantly. Out of all the spraying schemes, the one using K2.0 nozzles at a spraying pressure of 8 MPa achieved the most favorable dust suppression performance, and the dust suppression efficiency in a fully-mechanized excavation face was as high as 86.1%; meanwhile, the proportion of respirable dust with a diameter smaller than 7 mu m increased gradually from 16% to 27%. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.