| The presence of high dust concentrations in heading workface, it leaded toenvironment polluted and it also posed a serious threat to workers’ health andsafety in production of the mine.The wet drilling and spray of boring machinehave adopted in wet dust suppression for heading workface,and achieved a goodcontrol effect.But there are still some shortcomings:nozzles easy to plug and lowdegree of atomization.To achieve a low dust concentration,it also need to usepressurized equipment for the water,which lead to be complex for the overallstructure of the dust equipment.Water consumption was higher in spray system,it was easy to produce water phenomenon and accelerated the corrosion rate ofmachinery and equipment.So it is important to develop a simple and efficientdustfall equipment.The dust distribution regularity in forced ventilation of the headingworkface was stimulated by using the discrete phase mode.The results show thatthe dust concentration is higher in front of roadheader,then generally decreasesslowly and finally tends to be stable.In the two sides of roadheader,the dustconcentration in the return air side is higher than the push air side.According to the dust distribution regularity by numerical simulation andmeasures of reducing dust concentration in heading workface and combinedwith the advantages of gas-water atomization,the circulation gas-water atomization dustfalll device was designed.The device has two working modes:the first is the using compressed air directly impact on liquid which ejected fromthe tapered girth to form droplet,which referred to as air impact atomizationwork mode;the second is that the compressed air through the tapered girth tospray and generate a negative pressure in the device,leading to droplets whichejected by spray nozzle are introduced into a high velocity airflow for secondbroken,which referred to as the negative pressure introducing droplet brokenatomization work mode.The device don’t use pressurized equipment and rely onthe ventilation pipe and tunnel water in the heading workface to supply thepower of gas and water.It has advantages of simple structure,low waterconsumption and a good effect of dust suppresssion.The flow filed of gas and water of the device in the mode of air impactatomization was simulated by using the computational fluid dynamics softwareFluent,and the effect of different inlet velocity on the gas and water to the deviceflow filed was analyzed.Results show that in the gas phase flow field,the closerto the center line of device, the higher value of airflow velocity was;The flowfield can be divided into the recirculation zone, eddy zone, separation zone andthe mixing zone according to the flow characteristics in the liquid phase flowfield.The effect of girth angle and trachea on the water flow filed was alsoanalyzed,the range of optimal parameters about optimum atomization of thedevice were obtained:the girth angle should be between40°~50°,the tracheadistance should be between2~6mm.The gas flow filed of the device in the modeof negative pressure introduced broken was also simulated,the effect of gaspressure on the gas flow filed was also analyzed,atomization process in thismode was numerically simulated.Based on the numerical analysis,considering the air consumption,waterconsumption,conical girth blockage and other factors,two modes of atomizationfor the device were compared from theory.When the device used in headingworkface,the work mode about the negative pressure introducing droplet broken atomization should be choosed in preference.Finally,the device in the work mode of negative pressure introducingdroplet broken atomization was studied by experiment from spray characteristicsand dustfall properties.The results show that the droplet size of the devicedecreases with gas pressure increasing in the work mode.The dustfallexperiment shows that the device is able to achieve the requirements aboutreducing dust concentration in heading workface,and it has a broad applicationprospects. |
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