| In the place where coal dust is deposited underground,once the gas explosion causes the coal dust to suspend in the air,the raised coal dust concentration will cause a secondary explosion of coal dust as long as it reaches the lower explosion limit of30-50g/m~3.Compared with the primary gas explosion,the secondary coal dust explosion is a secondary destruction based on the existing destruction,and its harm is far greater than the simple gas explosion;And there are many obstacles in the coal mine,which can promote the gas explosion to a certain extent.In order to prevent and control the secondary explosion of coal dust deposited by gas explosion winch,it is necessary to study the influence of internal factors and environmental factors on the secondary explosion characteristics of coal dust deposited by gas explosion winch from its influencing factors.In this paper,theoretical analysis and experimental research methods are used to study the secondary explosion law of coal dust entrained by gas explosion in closed pipes,revealing the influence of gas concentration,coal dust concentration and coal dust laying position,as well as the number and spacing of obstacles on the secondary explosion characteristics of coal dust entrained by gas explosion.The main contents and achievements are as follows:Firstly,the influence of gas concentration,coal dust concentration and coal dust laying position on the secondary explosion characteristics of coal dust deposited by gas explosion winch was studied in the closed pipeline.The results show that the explosion intensity and flame propagation velocity of 10%gas concentration are higher than those of 8%and 12%under the same conditions when the single gas concentration changes.When the gas concentration is 8%,10%and 12%respectively,the influence of coal dust concentration on the explosion characteristics is not the same.When the gas concentration is 10%,the explosion intensity of coal dust concentration is higher than other concentrations of coal dust when the gas concentration is 250g/m~3;When the gas concentration is 8%and 12%,the explosion intensity gradually increases with the increase of coal dust concentration.When the coal dust concentration is 1000g/m~3,the explosion intensity is the highest.When the gas concentration and coal dust concentration are constant,and the coal dust laying position changes,the explosion intensity and flame propagation speed when laid 0.5m in front of the pipe in the coal dust section are higher than 0.5m behind the pipe,and the arrival time of the flame front is lower than 0.5m behind the pipe.Secondly,gas concentration,coal dust concentration and coal dust laying position are selected to study the influence of the number and spacing of obstacles on the secondary explosion characteristics of coal dust deposited by gas explosion winch.The research shows that when the distance between obstacles is fixed,with the increase of the number of obstacles,the number of times that the explosion shock wave and combustion wave in the gas section are disturbed when passing through the obstacles increases,and the turbulence effect on the methane premixed gas is more obvious.The combustion wave disturbance generated by gas explosion increases,and the flame accelerates,which shortens the arrival time of the flame front at each measuring point in the coal dust section pipeline,increases the flame propagation speed,and the peak explosion pressure overall shows an upward trend,The time required to reach the peak explosion pressure is shortened.When the number of obstacles is fixed,with the increase of the distance,the change trend of the peak explosion pressure and the time required to reach the peak explosion pressure is the same as that of the number of obstacles.While the flame consumes less energy in the propagation process,it can be fully disturbed to cause the flame to accelerate,so that the time to reach each measuring point is shortened and the flame propagation speed is increased.Figure 34 Table 20 Reference 98... |
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