| It is very difficult to control the dust in the comprehensive excavation work,especially when cutting the half coal rock section with high Proctor coefficient and low moisture content,the problem that the dust concentration in the head-on and roadway exceeds the standard seriously threatens the health and safety of the underground workers.In this thesis,a comprehensive mining face in Shaanxi Province is taken as the research object.Through field measurement and simulation analysis,the distribution law of air flow field and dust field in the comprehensive mining face under two ventilation modes and the influence of working condition parameter changes on the dust removal effect are studied.In view of the problem that the dust of flour in the comprehensive excavation is seriously over the standard,this thesis puts forward a dust removal system scheme that uses the combination of air curtain dust control,pressure and suction(with dust removal fan)combined ventilation,and discusses the configuration relationship between the system parameters.The main work of this thesis is as follows:(1)The field investigation and data measurement of the comprehensive excavation face are carried out.The wind speed,dust concentration and dust sampling data of the measurement points in the comprehensive excavation face are statistically sorted out.The dust dispersion is calculated by the least square method and verified by MATLAB.The modeling parameters and validation data are provided for the simulation analysis.(2)According to the equipment layout of the working face,a three-dimensional geometric model is established;according to the theory of gas-solid two-phase flow,the numerical simulation of the air flow field and dust field in the comprehensive excavation working face under the single forced ventilation mode is carried out by using FLUENT software,and the effectiveness of the simulation model is verified by comparing the measured data.(3)This thesis analyzes the distribution of air flow field and dust field in the fully mechanized excavation face under the two ventilation modes of single pressure type and pressure and suction(with dust removal fan),as well as the influence of the change of pressure outlet position of local fan on the distribution law of air flow field and dust field under the combined ventilation mode of pressure and extraction(with dust removal fan).The results of simulation and measurement show that the average dust concentration in the respiratory zone of Fully Mechanized Driving Face under the two ventilation modes is far beyond the national standard.(4)A dust control and dust removal system is proposed,which uses air curtain jet to control the dust of fully mechanized excavation face within 0-5 m of the head-on face,and then exhausts and filters the dust in the control area by wet vibrating string dust removal fan.Firstly,the functional relationship between jet velocity,outlet width and entrainment air volume of dust control air curtain is derived based on the principle of impinging jet;then,the two-phase flow simulation model of air curtain dust control and dust removal system is established;finally,the influence of system configuration parameters(initial jet velocity,outlet width,jet angle and pressure outlet position of local fan,etc.)on dust removal effect is studied The optimal configuration parameters under the fully mechanized driving face.The results show that the dust removal effect of the system is significantly improved compared with the combined ventilation of pressure and suction fan(with dust removal fan)when the system operates under the optimal configuration parameters,which is close to the national standard. |
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