Experimental Investigations on Explosion Characteristics of Different Ranks Coal Dust in Horizontal Pipeline

To study the explosion characteristics of coal dust samples with different metamorphism, 19 coal samples including anthracite, bituminous coal, lignite were selected, explosion pressure distribution and flame propagation velocity were studied in an explosion pipeline with an outer diameter of 108 mm and an inner diameter of 88 mm. Coal dust particles were injected into the pipeline by eight dust nozzles controlled by solenoid valves. The explosion pressure and flame propagation profiles were obtained by PCB piezoelectric sensors and photoelectric sensors. The experimental results suggested that the explosion pressure profiles of different coal samples are all present a first increasing and then decreasing trend. However, there is a drop point at 0.875 m from the ignition end. The flame propagation velocity increases first and reaches the maximum at 0.625 m from the ignition end, and then the propagation velocity begins to decrease until the end of the pipeline, while there exist a slight enhancement at 1.105 m from the ignition end. Furthermore, the coal samples with different coal ranks have different explosion severity, coal samples with lower moisture content, and relatively higher volatile matter present a better deflagration property and cause a higher explosion severity.