Supersonic siphon suction water aerodynamic atomization in dust removal

High-concentration respiratory coal dust has remained as a serious hazard in the coal mining industry for a long time. The wet method currently used has many weaknesses, such as no clear targets, low efficiency of dust collection, high energy consumption and poor reliability. To solve the problems above, the dust reduction technology using supersonic suction siphon aerodynamic spray has been proposed in this study. The Fraunhofer diffraction principle is used to determine the particle size distribution of the external spray field. The near-field droplet size and the velocity distribution characteristics of spray field at the 0-30 cm distance to nozzle outlet, which cannot be obtained by experiments, are simulated and studied by using the CFD-FEM method, and the Spalart-Allmaras and droplet breaking particle tracking module of COMSOL software. Through the comparison experiments of dust control with ultrasonic dry spray dust suppression technology, the dust control characteristics and mechanism of the technology are obtained. With experimental research, the influence of different working condition parameters and nozzle outlet taper on atomization energy consumption and dust reduction rate are obtained. The results show that the designed atomization dust reduction device can achieve the micron-level, high-dynamic atomization effect of the negative pressure suction siphon process under the aerodynamic pressure as low as 0.2 MPa. At 0.6 MPa, the particle size distribution range is 1.00-21.87 μm, and the number of the droplets below 10 μm accounts for 90% of the total droplet number below 100 μm, and more than 80% below 5 μm. The droplet speed is fast and the range is large. The number concentration of the droplet speed above 160 m/s accounts for 50%, and above 50 m/s accounts for 99%. The air consumption and water consumption are low, and the spray angle is in the range of 60°-95°. The dust reduction rate is 1.5 times of that using the ultrasonic dry spray dust suppression, and it increases with the increase of the droplet concentration and speed, and the instantaneous efficiency is increased 2%-26%. At the same efficiency, the proportion of dust below PM10 reduced 24%. After being applied in the 06 return air way of Mindong No. 1 Mine, although it was disturbed by the wind flow with a central wind speed of 0.86 m/s, it still penetrated and covered the entire section, and the dust reduction efficiency for respiratory coal dust reached more than 88.8%. It is proved that the system can achieve low humidity, water saving and efficient dust control effects.