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 D(50), 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.