Numerical Simulation Research On The Migration Of Airflow And Dust In Respiratory Zone Of Fully Mechanlzed Mining Face With Large Mining Height

With the development of science and technology,there are more and more fully mechanized mining face with large mining height With the application of large-size and high-power machinery and equipment,the mining intensity makes the coal mining efficiency increase rapidly.However,improvement of mining intensity and efficiency will lead to a sharp increase in dust concentration,and the existence of large machinery and equipment makes the airflow distribution change in fully mechanized mining face complieated,and the dust mass concentration distribution in different areas and heights of mining face space is also different.Dust not only harms the health of underground workers,but also aggravateg the equipment loss and causes the deterioration of the working environment Therefore,it is of great significance for dust control to study the distribution of dust mass concentration and its variation trend along the respiratory zone of the mining face,as well as the Main factors affecting the dust distribution.This paper is based on gas-solid two-phase flow,dust features and other theories,and using computer software such as FLUENT.By combining theory analysis principle,field measurement and numeriical slmulation,the experiment and numerical simulation were carried out on the full-mechanized mining height under the condition of multiple processed and dust sourees.The research contents and results are as follows:Firstly,I researched the geometric model of mining face,the basic characteristies of mining dust and its physical model of migration.I established the mathematical models of dust migration,and an appropriate rumerical solution method is raisedSecondly,through field observationd,the paramcters such as dust particle xize distribution,dust dispersion and mass concentration at different locations of the fully mechanized coal mining face were measured.The boundary conditions,discrete phase and continuous phase parameters of the model are determined based on the analysis and calculation results of the measured data.It is prepared to simulate the velocity field and concentration field distribution of coupled gas-dust transport in the whole fully-mechanized mining face.Finally,numerical simulation is carried out to study the fully mechanized face with large mining height.In the case that the wind speed is 1.5m/s and multiple dust sources are generated in various production processes,the distribution of wind flow,the distribution law of dust mass concentration in breathing zone and the main influencing factors is discussed.By adjusting the parameters to simulate the influence of different wind speeds and different mining height on the dust mass concentration and wind flow distribution in the breathing zone.I find out the key dust control area and the main factors affecting dust diffusion.Then I I optimized the site ventilation and wind speed and dust control measures.According to the research results,the change and distribution of turbulence and air flow in large-height fully mechanized mining face are obviously affected by obstacles in the face.To avoid turbulence caused by the sudden change of space cross-sectional area,obstacles in the mining face should be reduced,and dust should be widely dispersed in the mining face under the influence of turbulence.The higher the wind speed within the specified range,the more favorable it is to reduce the high dust mass concentration in the respiratory zone of the mining face.However,excessive wind speed is easy to cause secondary dust,so the best ventilation wind speed of 6m large mining height mining face should be about 2.5m/s.The respiratory zone with high dust mass concentration is within 20-50m from the leeward side of the large-height fully mechanized mining face.And the high proportion of respiratory dust in the respiratory zone is the key area for dust prevention and control.In this range,the dust floating in the breathing zone can be rapidly settled.Spray dust removal equipment or preferably surfactant can be used as dust removal agent for targeted dust removal.