Dust reduction technology of supersonic coaxial aerodynamic atomization

In the process of coal mining, a large amount of respirable dust is generated, which seriously endangers the miners’ health. As the most widely used dust reduction technology, the spray technology has the advantages of high efficiency and cleanliness, but the existing spray technology does not have a strong ability to capture respirable dust, and the atomization efficiency is low. In order to solve those problems, the supersonic coaxial aerodynamic atomization technology was developed. The atomization characteristics of the technology were studied by experimental and numerical simulations, and the dust reduction characteristics of supersonic water drawing siphon aerodynamic atomization and supersonic coaxial atomization were compared based on the self-designed dust reduction experimental platform. At the same time, the dust separation experiment of the two technologies revealed the sedimentation mechanism of dust under the action of supersonic dynamic micro-fog curtain. The results show that under different aerodynamic pressures, the coaxial probe water injection method adopted by the supersonic coaxial atomization dust reduction device greatly reduces the energy loss of the probe structure on the supersonic flow field, significantly improves the atomization efficiency, and produces a large number of high-speed droplets below 11 μm with an uniform spatial distribution, and the particle size is reduced by 12%−50% compared with the siphon atomization device, forming a large-scale high-speed fine fog area in the spray flow field. The coupling effect of the droplet field and the dust field can be characterized by the instantaneous dispersion of the dust and determined by the distribution characteristics of the droplet field. At different times, the variation trend of the graded dust reduction efficiency in each particle size interval is different, and the contribution to the total dust reduction efficiency under different pressures is also different. The large-scale high-speed fine mist generated by the supersonic coaxial atomization technology is easy to capture respirable dust, and the classification efficiency of PM₀−PM_2.5 is more than 75%, and the maximum is 90%. The increase of pressure enlarges the range of high-speed fine mist, which is conducive to the capture of fine particles. During the confined space migration of dust-containing airflow, the sedimentation process of dust under the action of supersonic dynamic micro-fog curtain can be divided into droplet dust capture area, condensation and sedimentation area, and evaporation escape area. The different behaviors and concentration distributions of fog droplets and dust in different regions are the results of the drag migration of spray airflow and airborne wind flow, the capture of high-speed micro-fog collision, the condensation and settlement of fog droplets, and the weight loss of fog droplet evaporation.