Abstract
In order to effectively reduce the coal dust concentration in a fully mechanized mining face, this research used laboratory experiment, numerical simulation, and field test to conduct an in-depth exploration of the ejector precipitator installed at the low-level caving coal hydraulic support. Firstly, through the experimental platform in the laboratory, the dust removal effect of the nozzle with different structural parameters was tested, and the 3D particle dynamic analyzer was adopted to verify its atomization characteristics; then, the structural parameters corresponding to the nozzle in the best test results were obtained. Secondly, by using Fluent, the negative pressure flow field in the ejector barrel was numerically simulated. The results indicated that when the pressure of supply water was 12 MPa, the negative pressure value formed in the flow field was the lowest and the inspiratory velocity was the largest, which was conducive to dust removal. Finally, the tests of liquid–gas ratio and dust removal ratio were carried out in a fully mechanized mining face. The results showed that when the nozzle specification recommended by the experiment and the pressure of supply water recommended by the numerical simulation were used, the removal ratios of the total coal dust and the respirable coal dust were 89.5% and 91.0%, respectively, at the measuring point of the highest coal dust concentration. It indicates that the ejector precipitator has a good application effect in reducing the coal dust concentration in a fully mechanized mining face and improving the work environment of coal mine workers.
Highlights
At present, workplace pollution has become an important scientific research topic, which is of vital significance to the health of workers
Under particle dynamic analysis (PDA) laboratory conditions, the uncertainty caused by environmental interference and signal-to-noise ratio was less than 0.05 dB in amplitude and less than 1° in phase
Negative pressure zone appeared around the nozzle and somewhere of the pipe wall, the negative pressure at the nozzle was caused by a high-speed water jet
Summary
Workplace pollution has become an important scientific research topic, which is of vital significance to the health of workers. If no dust removal strategy is adopted, the concentration of the coal dust can rise to 8000–10,000 mg/m3 in a fully mechanized mining face, which has caused irreparable harm to the physical and mental health of the coal miner [4,5,6]. In order to valid control the pollution degree of coal dust, some dust removal strategies including coal-seam water injection, dust removal with chemical reagents, dust removal by ventilation, bubble scrubbing, and spray dust removal are adopted; the spray dust removal has many incomparable advantages including strong operability, low failure rate, and low cost and is frequently used in coal mine site at present [13,14,15,16,17,18]. The researches of spray dust removal technology by researchers are centered on two aspects, i.e., experimental study on atomization characteristics of nozzle spray and numerical simulation of multiphase flow coupling in the spray field.
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