Dust Reduction Technology And Engineering Application Of Gas-liquid Two-phase Jet Micro Water Mist In Fully Mechanized Mining Face

The fact that China’s energy structure is dominated by coal is difficult to be fundamentally changed in the short term.Dust is generated in all major coal production stages and the rapidly developing large-scale mechanized coal mining process has led to an exponential increase in absolute dust production.Coal mine dust will remain a longterm hazard to safe production and miners’ health.The fully-mechanized coal mining face is one of the main sources of dust production.Respiratory dust generated during mechanical operations is extremely hazardous to the health of miners,and there is an urgent need to carry out research on respiratory dust reduction technology in the fullymechanized coal mining face.In this paper,we use theoretical analysis,numerical simulation and experimental research to address the issue of respiratory dust prevention and control in fullymechanized coal mining face.A large number of studies have been conducted,including research on the coupling motion of dust and gas,research on the mechanism of fine water mist dust reduction,research on the law of self-settling of respirable dust,research on the effect of droplet size on respiratory dust capturing by fine water mist,and research on the effect of air humidity on respiratory dust capturing by fine water mist,as well as research on the mechanism of fine water mist dust reduction by gas-liquid two-phase flow spray in fully-mechanized coal mining face and engineering application.The main innovative results achieved are as follows:The relationship between the basic properties of dust and its probability of being captured by mist droplets is analyzed through the research on the basic properties of dust in fully-mechanized coal mining face;The conclusion that,wind flow is the most important factor affecting the distribution of respiratory dust in fully-mechanized coal mining face,is drawn from the analysis of the force model of dust particles in the Face;Research on dust capturing theory and gas-liquid two-phase flow spraying fine water mist dust capturing theory to analyze the factors affecting the efficiency of gas-liquid twophase flow spray dust reduction.The atomization performance test system of gas-liquid two-phase flow nozzle has been designed,a large spray dust reduction test tunnel has been built,and the mechanism of dust reduction and dust capturing law of gas-liquid two-phase flow spraying fine water mist has been studied.Based on the research of the working principle of a new gas-liquid two-phase flow nozzle and the testing of its atomization performance,the atomization performance of the new nozzle under different air pressure and water pressure was obtained.Experimental research on dust reduction law and mechanism of dust reduction by spraying fine water mist for gas-liquid two-phase flow in a large spray dust reduction test tunnel.According to the experimental data,the law of respiratory dust capturing by droplet particles with different median diameters and different particle size ranges is obtained,and it shows that the spray with a median diameter of 9.00 μm and particle size range of [5.95,14.52] μm has the best effect on respiratory dust capturing.The tests on respiratory dust capturing of six different median diameter droplet particles show that the peak values of respiratory dust capturing rates for droplets with median diameters of 9.00μm～29.87 μm,49.85 μm～75.85 μm,116.47 μm occur at the range of [5.0,10.0]m,[15.0,20.0]m,[20.0,25.0]m,respectively,from the dust source point.The qualitative analysis indicates the important role of the coalescence mechanism in respiratory dust capturing.By experimenting and searching the effect of humidity on respiratory dust catching efficiency and quantifying the role of the coalescence mechanism in respiratory dust capturing,a relationship has been obtained between the variation of humidity in the region of [10.0,40.0] m from the dust source and the respiratory dust capturing efficiency.Fluent software was utilized to study the transport and concentration distribution patterns of dust in 22410 fully mechanized mining face of Halagou Coal Mine.The existing dust concentration measurement method of fully mechanized mining face was improved,and a new type of auxiliary equipment for dust concentration measurement of fully mechanized mining face was designed.The concentration of respiratory dust near the main dust source point of 22410 fully mechanized mining face was measured to verify the accuracy of numerical simulation results.Based on the force analysis of respirable dust particles,research on the effect of particle size on dust capturing by fine water mist,research on the effect of coalescence mechanism on respirable dust capturing,and research on the transport law of respirable dust in fully-mechanized coal mining face,a system of dust reduction by gas-liquid twophase flow spraying fine water mist in fully-mechanized coal mining face has been designed and developed,which has been applied to #22410 fully-mechanized coal mining face in Halagou Coal Mine.The efficiency of the dust reduction system in respirable dust capturing is significantly improved in comparison with the original high-pressure spray dust reduction system.Figure [70] Table [63] Reference [152]...