Study On Dust Control Technique By Air Curtain For Heading Face In Thin Coal Seam

The driving face of thin seam features small work space and quick construction work,which makes dust accumulation and dust concentration over its standard.Based on the condition of level driving face,namely negative 290 m,the paper studies lower dust concentration of roadway through dust control by air curtain.After analyzing the theory,the paper concludes that the dust's main driving force to move backward roadway is air current movement.The air current of driving face includes jet zone,downstream zone,vortex zone and reverse zone.The best way of airing is U-typed wall-attached laminar flow.By building two-phase flow model of gas and solid,we get that volume of air supply stands at 250m3/min,the length of jet zone of air current and air outlet of hair dryer is close while the distribution zone of dust lowers.When Lf equals 6m,the driver position is influenced less by disturbance wind speed and dust of return current.At the same time,quicker disturbance wind speed of cutting head will make the distance of dust to heading machine longer and dust zone of hoeing coal petrography larger.The more dust brought by heading machine,the more average dust concentration of roadway.When dust J of cutting head exceeds 120mg/s,the respirable dust concentration of driver position of heading machine and back work space will seriously violates national standard.Opening air curtain will forms impact jet flow,including free jet flow zone,jet impact zone and wall-attached jet flow zone.By analyzing the relations between width of air curtain wind outlet and wind volume of air curtain,small width of outlet will improve wind speed of air curtain of heading face,which will achieve wind volume of air curtain.When wind speed of outlet stands at Vq equals 7.0m/s,the dust concentration of driver position of heading machine is lower.When dust concentration of back work space X1 is greater than X2,the high dust concentration zone is controlled near return air and the control rate of air curtain is high.Lengthening draught fan of diversion air curtain of return air alone will lower dust concentration of driver position of heading machine and back work space.When the length of draught fan of diversion air curtain of return air is LFz2 equals 3m,the controlling effect of heading face is favorable.Comparing conditions of opening air curtain or not,we get that when dust concentration of driver position of heading machine lower by 76.92% to 3.5972mg/m3,it meets national standard.Experiment study based on wet dust removal of mine reveals that when width of air curtain outlet,wind speed and angle of tilt stands at 0.02 m,7m/s and 10°,the controlling effect rate of air curtain registers up to 82.3%,which conforms to theoretical analysis and numerical modeling results.