Development and application of air-assisted spraying device for dust suppression on tunnel boring machine

For the current problems of high water consumption, low dust suppression efficiency, and poor long-distance dust suppression effect of the spraying device on the tunneling machine in the coal mine comprehensive mechanized excavation working face, a novel air-assisted spraying device for dust suppression on tunneling machine was designed in this study. The basic characteristics of the flow field and spray field of the air-assisted spraying device for dust suppression on tunneling machine were analyzed by the computational method of CFD numerical simulation. The optimal operating parameters of the device were explore. The device was applied to the stone drift working face to test its dust suppression efficiency on the site. The results of the study showed that the air-assisted spraying device for dust suppression on tunneling machine, based on the principle of the Coanda Effect, can produce a diversion effect, effectively improving the atomization effect and dust suppression efficiency of the device and reducing its water consumption. This device can blow the spray to a distant dust suppression area to achieve long-distance dust suppression; and the rear of the device can suction the surrounding dusty gas, which is then sprayed out together with the mist, achieving a secondary dust suppression effect. The rational gas supply pressure and water pressure for application at the coal mine comprehensive mechanized excavation working face are 0.4 MPa and 2.0 MPa, respectively; the optimal installation angles for the nozzle and the spray cylinder are 45 and 30 degrees, respectively. The results of on-site test showed that the device can effectively reduce the dust concentration in the working face of the tunneling machine, with an average dust suppression efficiency of 61.39 % and 43.19 % for total coal powdered and respirable coal powdered, respectively. After adding the air-assisted spraying device for dust suppression on the tunneling machine, the dust suppression efficiency for total coal powdered and respirable coal powdered showed a relative improvement of more than 30 %.