Research And Application Of Radial Swirling Air Curtain Dust Control Technology In Fully Mechanized Working Face

The rapid development of mechanization of the digging technology leads to a high instantaneous total dust concentration of the fully mechanized working face which can reach to 2500?3000mg/m3,the dust pollution has threatened the physical health and the safety production of miners.The achievements of domestic and foreign scholars show that air curtain dust control technology can prevent the pollution caused by high concentration dust diffusion effectively.To grasp the influence law of the ventilation conditions to the formation,migration and dust control of the air curtain and to achieve the optimal air curtain dust control parameters for fully mechanized working faces with different section types,the combination of theoretical analysis,numerical simulation,experiment test and engineering application was adopted in this dissertation.The achievements of this dissertation can provide a good theoretical and technical basis for the prevention and control of dust pollution in fully mechanized working face.The cutting-dust generation theory was theoretical analyzed.The basic characteristics of those coal and rock cutting dust were measured by Mastersizer 3000 laser diffraction particle size analyzer,the particle diameter distribution law of those samples were achieved and provided basic data for numerical simulation studies.According to the air-dust movement equations of fully mechanized tunnel and the plane impinging jet theory,the velocity and turbulence of airflow were the main controlling factors of dust diffusion states was clarified,the radial swirling air curtain dust control theory was also expounded.Based on the Realizable?-? model,particle force equations and the stochastic trajectory model,the air-dust two phase flow in fully mechanized working face was numerically simulated by ANSYS Fluent.The formation,migration and dust control laws of air curtain in fully mechanized working faces with different sections under various ventilation conditions were showed that when the exhaust air duct was installed near the wall in the opposite side of the pressure air duct,the longer the distance between wall-attached ventilation duct and working face,at the same time,the larger the radial to axial airflow quantity ratio,the smaller the pressure pumping ratio and the shorter the distance between air-inlet of exhaust air duct,then the better the radial swirling air curtain transformed into an effective axial dust control air curtain and the shorter the high concentration dust diffusion distance.The radial swirling air curtain dust control experimental system of fully mechanized working face was established,the performance of the improved combined flexible lightweight wall-attached ventilation duct was validated by this system.On the basis of the above,the airflow velocity and direction,the time-consuming of air curtain generation and the dust concentration distribution were tested under various ventilation conditions.The influence laws of ventilation conditions to radial swirling air curtain dust control were verified through this experiment and the optimal air curtain dust control parameters for fully mechanized working faces with different section types were furthermore revealed,which were the distance between air-outlet of dust removal fan and working face>the distance between wall-attached ventilation duct and working face?20m,radial to axial airflow quantity ratio of wall-attached ventilation duct?0.8,pressure pumping ratio of ventilation system?0.75 and the distance between air-inlet of exhaust air duct and working face?3m,the effective axial dust control air curtain can be formed rapidly in front of digging driver to avoid the diffusion of high concentration dust.Based on the above achievements,the radial swirling air curtain dust control systems were constructed and applied in 3down612 conveyance tunnel of Jiangzhuang coal mine,intake airflow tunnel of east-fifth mining area of Huipodi coal mine and 63up08 transportation roadway of Dongtan coal mine.The results showed that the effective axial dust control air curtains were formed in the section in front of the mining drivers in these working face,a good dust control effect was achieved and the working environment in fully mechanized working face was improved obviously.