Abstract

An experimental study on the flow rate and atomization characteristics of a new gas–liquid two-phase flow nozzle was carried out to use high-concentration respirable dust in the workplace of high-efficiency sedimentation coal production based on the gas–liquid two-phase flow nozzle technology. The simulation roadway of dust fall in large coal mines was constructed, and the respirable rock dust produced by fully mechanized mining surfaces was chosen as the research object. The effects of humidity on the capture effect of respirable rock dust were analyzed in the experimental study. The results demonstrated that: (1) the distribution range of the particle size of fogdrops declines with the reduction in fogdrops D50, D[3,2] and D[4,3], which are produced by gas–liquid two-phase flow nozzles. (2) The initial ambient humidity in the simulated roadway was 64.8% RH. After the gas–liquid two-phase flow spray was started, the ambient humidity was elevated by 23.2 to 23.5% RH within 840s and tended to be stable and no longer grew after reaching 88.0–88.3% RH. The initial growth rate of the ambient humidity in the simulated roadway was high, and then was gradually slowed down. (3) Humidity is an important factor influencing the collection of respirable dust. The humidity at 10.0 m leeward of the dust-producing point was increased by 19.6% RH, and the sedimentation rate of respirable dust was increased by 6.73%; the two growth rates were 13.1% RH and 9.90% at 20.0 m; 16.4% RH and 15.42% at 30.0 m; 18.4% RH and 11.20% at 40.0 m. In practical applications of the gas–liquid two-phase flow nozzle in coal mining activities, attention shall be paid to not only the influences of its atomization characteristics on the capture effect of respirable dust but also the influences of the flow rate of the nozzle on the humidity of the working surface. Appropriate gas and water supply pressures shall be chosen according to the space and respirable dust concentration on the working surface to realize a better dust removal effect.

Highlights

  • Recently, dust pollution of the fully mechanized mining surface in underground coal mines has become increasingly prominent with the continuous improvement of the mechanization level and gradual growth of mining intensity [1,2,3,4]

  • The gas–liquid two-phase flow nozzle has a good effect in the capture of dust, especially to respirable dust [10,11,12,13,14]

  • Water entered the large chamber through the flow channel, and the large channel was provided with a throttle lever to limit the flow and control the speed of the water, increase the relative speed between the water and gas, maximize the atomization effect of the gas to the water in unit area, and achieve a good atomization effect of the two-phase flow nozzle under low air pressure

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Summary

Introduction

Dust pollution of the fully mechanized mining surface in underground coal mines has become increasingly prominent with the continuous improvement of the mechanization level and gradual growth of mining intensity [1,2,3,4]. The current research on the mechanism of gas–liquid two-phase flow spraying dust reduction in coal fields mainly focuses on inertial collision dust trapping and diffused trapping. Related studies have been carried out on this basis, and it has been found that the ambient humidity in the roadway is the main factor influencing the respirable dust collection efficiency of gas–liquid two-phase flow spray. For the purpose of testing the atomization characteristics of the new gas–liquid twophase flow atomization nozzle, running water was used as the liquid phase medium, and the air was used as the gas phase medium. It is mainly composed of a water supply device, air supply device, test device, injection device and other parts. Under the effect of compressed air, the water was injected from the spraying nozzle through atomization. The data, including the pressure, atomization volume of steam, and air consumption, were recorded

Large Dust Reduction Experimental Tunnel System
Experimental Schemes
Respirable Dust Capture Effect of the Gas–Liquid Two-Phase Flow Nozzle
Conclusions
Full Text
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