Experimental Study On Dust Suppression Characteristics Of Swirling Fine Water Mist

With the improvement of mining machinery level,efficient and intensive mining has increased the efficiency of coal mine production.At the same time,the production of dust is increasing.Therefore,as one of the five major disasters in coal mines,mine dust is attracting more and more attention from the industry.Coal dust is a potential killer that seriously endangering the health of workers and damage to underground machinery and equipment.Its harmfulness has hysteresis and concealment,so it is the focus of coal mine safety production and occupational health and safety management.There are two main categories of mine dust control technology at home and abroad.The first one is active dust prevention,such as coal seam water injection and pre wetting coal body.The second category is passive dust control,such as mechanical dust removal,water mist,dust removal,chemical dust removal,and dustproof equipment.The technology of spraying dust with water as the main medium is more widely used and the universality of this technology is very strong.It can meet the dust reduction aim of coal mine to a great extent.Based on the atomization mode of water mist and the self-designed experimental system of water mist and dust suppression,a mathematical model of atomization of rotating water mist is established.The interaction between rotating fine water mist and dust was analyzed theoretically,and the entrainment effect of gas liquid mist field during dust falling process was qualitatively analyzed.At the same time,the rotational tangential equation is derived.Taking the droplet survival time and atomization angle as parameters,the effective range of dust removal by rotating water mist is derived.The gas solid outflow field is represented by shunting and stratified motion,and the dust reduction advantage under the presence of entrainment effect and Magnus effect is obtained.The dust migration law and atomization characteristics of rotating water mist were simulated by FLUENT software.The simulation results show that the particle size distribution ranges from 0.5μm~178μm,and the average migration time of suspended particles is 3.06s.The dust concentration in the roadway is basically maintained below 1000mg/m~3.Along the direction of airflow,the concentration of dust gradually decreased.In the initial 0.5m range,the concentration of curve decreased by about 74.9%.In the process of Y=1.0m~0m,the dust concentration fluctuates within the range of 150~1600mg/m~3.After dust fall,the concentration of dust is greatly reduced,and the concentration is basically maintained at 20~50mg/m~3.On the whole,the dust reduction effect is very good,and the particle size range of rotating fine mist is 61μm~445μm.Based on numerical simulation,the atomization characteristics and dust reduction efficiency of rotating fine water mist were experimentally analyzed from three aspects of atomization pressure,swirl number and wind speed.The experimental results show that with the increase of spray pressure,the dust reduction efficiency of the rotating water mist increases gradually,in which the dust efficiency of the dust is increased from 75.73%to 86.75%,with a relative increase of 11.02%,and the respiratory dust from 66.87%to 78.53%,with a relative increase of 11.66%.With the decrease of the helix angle,the strength of the swirling flow is increased gradually,the dust efficiency of the dust is increased from 72.89%to 85.86%,the increase is 12.97%,the relative direct spray fine water mist increases by 10.56%,and the dust removal efficiency of the respirable dust increases from 68.71%to 77.19%.With the increase of roadway wind speed,the dust removal efficiency first increased and then decreased.The dust removal efficiency was the largest at 1.0m/s,which was85.62%and 74.29%respectively.But in the two cases of 0.5m/s and 1.5m/s,the dustfall efficiencies of full and respirable dusts were 79.71%,81.84%and67.59%,69.57%respectively.Finally,according to the experimental results,we get the best parameters of rotating fine water mist.Comprehensive research results show that the advantage of rotating fine water mist technology is not only able to provide some help for the spray and dust fall in coal mines,but also a reference value for the application of spray and dust fall technology.