Research Of Dust Movement In Roadway And Pipeline Deposition Law In Extractable Ventilation

Fully mechanized mining face is one of the main sources of mine dust,and it is also the most serious workplace of pneumoconiosis.Long-term inhalation of respirable dust(especially rock dust)will result in pneumoconiosis.Statistics show that more than 85%of the pneumoconiosis patients in coal mine have been engaged in rock roadway driving.The question is particularly urgent.The two major problems in the dust-proof ventilation of rock extraction roadway are how to control the dust diffusion and the problem of pipeline dust deposition.The use of pumping ventilation can effectively prevent the diffusion of respirable dust during the driving process of rock roadway,and its dust control effect is better than that of pressure entry ventilation and mixed ventilation.In this paper,the method of combining test and numerical simulation is used to study the distribution of wind speed,the law of dust migration and the dust deposition in the ventilation tunnel,which lays the foundation for the further study of the effective dust control measures,the deposition dust prediction and the cleaning technology.The main contents are as follows:(1)In the rectangular test tunnel with a section area of 12.24m~2,the wind speed distribution law under the condition of 120~160m~3/min is studied.6 test sections are arranged along the axial direction,and 24 measuring points are arranged on each section.The wind velocity distribution on different sections is obtained by measuring the wind speed of each point under the different wind volume Q.The distribution of wind velocity distribution coefficient K on different sections and the regularity of the variation along the axial direction of the tunnel are calculated.The results show that the wind speed distribution in the cross section of the wind inlet is the most uneven,and the velocity distribution uniformity behind the duct is better than that in the front of the wind tunnel.The change of K with the change of Q is not obvious.(2)Ansys Fluent software is used to simulate the relationship between 3laneways(arch,rectangular,trapezoid),air volume Q,the distance between the air inlet and the heading face L,the diameter D of the wind tunnel,the position of the wind tunnel on the tunnel section and the wind flow distribution,and the shape of the roadway is obtained.The variation of the diameter of the wind tunnel has little influence on the distribution of the wind speed in the tunnel.The K does not change with the change of the Q.The change of L changes the uniform coefficient of the wind velocity distribution in different roadway sections,and the change of the position of the tunnel section of the tunnel has a certain influence on the wind velocity distribution in the front of the wind tunnel.Through the comparison and analysis of the wind speed V distribution law obtained at different Q by the test and numerical simulation,it is concluded that the uniform coefficient of wind velocity distribution in the tunnel section of the air inlet and the rear section of the wind tunnel is less than that of the numerical simulation,and the numerical simulation parameters are corrected to make the numerical model.The simulated results are close to the experimental results and better guide the field practice.(3)Under the condition that Q is 150m~3/min,L is 3m and D is 600mm,through the combination of experiment and numerical simulation,the distribution law of dust concentration along the tunnel axis is studied at the height of the tunnel section from the height of the ground to the position of 1.5m.Both the experimental and numerical simulation results show that the dust concentration in the front of the inlet of the air inlet is rapidly decreasing,and the dust concentration in the rear air inlet of the wind tunnel is greater than the numerical simulation value.The influence of the variation of L and Q on the change of the average dust concentration in the roadway section is analyzed by numerical simulation.The results are as follows:(1)when L is selected 5values in the 1.5~3.5m range and Q is 150 m~3/min,the dust concentration value corresponding to the roadway section increases with L;and when L is 2.5m and Q is divided into 5 groups,it corresponds to the roadway broken flour.The concentration of dust decreases with the increase of Q.(4)Under the condition that the wind speed V is 5~16m/s and D is 600mm,the law of dust deposition in the duct is studied by means of the combination of experiment and numerical simulation.The test shows that the dust deposition quality in the test tube is relatively high in the 5m range before the inlet of the air vents,and the dust deposition quality distribution is more uniform when the inlet of the air inlet is over 5m,and the dust deposition quality in the same test tube decreases with the increase of the wind speed.The relationship between wind speed,particle size and dust deposition quality is studied by numerical simulation.It is shown that the quality of dust deposition and single particle size dust deposition decreases with the increase of wind speed,and the range of single particle size dust deposition increases with the increase of wind speed.The results of comparison test and numerical simulation show that there are certain differences between the experimental and numerical simulation results.By modifying the numerical simulation parameters,the accuracy of the numerical simulation is improved and the reference to the field practice will be provided in the future.