Research On The Collection Of Respirable Dust By Spray In Fully-mechanized Face Of The Mine

This paper,starting with the environmental control of the mine,focused on the technical problems of the respirable dust spray in fully-mechanized coal mining working face.The article which was based on the working conditions of the 2612 fully-mechanized working face of a certain mine in Henan Energy studied the dust reduction of respirable dust on the fully-mechanized coal mining face by means of theoretical analysis,numerical simulation and similar simulation experiments.The main conclusions are as follows:(1)By analyzing the mechanism of hydraulic atomization and air atomization and giving the interpretation for different atomization processes and methods,this paper obtained the critical Weber Number for droplet crushing and calculated maximum particle size of droplet and critical relative velocity when droplet became broken.Of course,it shown the inverse relationship between particle size and relative velocity when the droplets were broken.(2)This paper analyzed the various mechanisms of action of mist catching dust,including the inertial collision,interception,gravity settlement,and the electrostatic force and diffusive effect of fog drop catching.By establishing a dust collection efficiency mathematical model based on collision and retention mechanisms,it can be concluded that with the increase of relative velocity,dust particle size and dust density,the dust collecting efficiency will rise,and as the droplet size decreases,the dust capture efficiency will also be improved.(3)By simplifying the mathematical model of the droplets in the airflow,it got the equations of motion in the droplets and in the airflow;then it was concluded that when the diameter of droplets were small,the horizontal speed was much greater than the vertical speed,and it would get an effective shooting range,improving the active collision of the droplets.Considering the natural evaporation time of droplet,we can conclude that droplet size should be considered between 50~100?m for capturing respirable dust.(4)Using FLUENT to simulate dust spray and compare dust droplets with different particle diameters to reduce dust,it was found that when the median diameter of the droplets was 50?m,the collection efficiency for respiratory dust could be better,and the average dust concentration drop ratio could reach to 80.12%.(5)Through experimental research,the concentration of dust concentration on the direction of the roadway increased first and then decreased.It reached a peak near the distance of 3m from the dust source,about 446.14mg/m~3.After that the concentration began to decrease.There was another conclusion that the dust concentration in the first half of the increase was greater than the decline in the second half.(6)After the spray was opened,the spray pressure was compared with the spray pressure to reduce the dust.And the spray pressure of 0.5 MPa can be used to achieve the best spray dust reduction effect.The average dust reduction rate was 80.6%and when the spray pressure was 0.5MPa,by comparing the droplet size distribution before and after the spray,it was concluded that when particle size of droplets was around 30-50?m,the respirable dust could be collected well.