Study on the influence of aerosol atomization by ultrasonic atomization on coal spontaneous combustion

Abstract

ABSTRACT Influenced by the complex environment and the nature of process materials in goaf, the prevention and control of spontaneous combustion of coal (CSC) in the deep part of goaf were facing many difficulties. To investigate the performance of ultrasonic atomized aerosols, a series of atomization experiments were conducted using a self-developed ultrasonic atomization device. The main conclusions are as follows: under the same atomization conditions, the atomized particle sizes of several inhibitors (except PAS-W) are concentrated in the <8 μm range, with a content of more than 88%, indicating that the aerosol particles produced by ultrasonic atomization are small in size and uniform in distribution. Compared with water and MgCl2 inhibitors, aerosol particles produced by PAS-W are less likely to pass through the voids of the coal body, and have poorer permeability and diffusivity. As the temperature increases, the viscosity and surface tension of the inhibitor decrease, and the percentage of aerosol particles with particle size <8 μm produced by ultrasonic atomization is more than 88%, indicating that the atomization effect is improved. After increasing the temperature, the contact angle between PAS-W inhibitor and coal reduces from 54.7° to 40.8°, and the wettability is better. Compared with raw coal, the final temperature of the PAS-W aerosol treated coal sample is delayed 21.86°C, and has significant retarding property. When the wind speed is 3 m/s, the effect of PAS-W aerosol particle generation, permeability, and particle size distribution is the best. The results of the study are of great significance in improving the ultrasonic atomized aerosol fire prevention technology and realizing large-scale CSC prevention in goaf.