EXPERIMENTAL STUDY OF THE EFFECT OF COAL DUST ON THE FLAME DYNAMICS OF PARTIALLY PREMIXED GAS-COAL DUST EXPLOSION IN A VERTICAL PRESSURE RELIEF PIPE-LINE

To further study the gas -coal dust explosion hazards under complex conditions. Experiments were conducted in pipe -line systems containing explosive pipe -line and pressure relief pipe -line. The effect of coal dust concentration and particle size on the flame dynamics of gas -coal dust explosion was investigated. The flame structure in the explosion pipe -line is divided into two -stages: spherical and round -finger. In the pressure relief pipe -line, the flame structure e varies at working conditions. Flame front position increases with time, showing a class exponential growth trend. The flame front velocity increases in the explosion pipe -line, has a short drop during the entry into the pressure relief pipe -line, and then increases. With the increase of coal dust concentration, flame propagation time has been increasing in the pipe -line system and the explosion pipe -line, with the shortest time at 25 g/ m(3). Flame propagation time first increases and then decreases in the pressure relief pipe -line, the shortest time at 50 g/m(3). The maximum flame front velocity first increases and then decreases. The maximum flame front velocity is maximized at 50 g/m(3). With the increase of coal dust particle size, flame propagation time has been increasing in the pipe -line system, and in the explosion pipe -line, flame propagation times have been decreasing in the pressure relief pipe -line. The maximum flame front velocity first increases, then decrease, and increases again. The maximum flame front velocity is minimal at 45 mu m.