Comparative study of the explosion pressure characteristics of micro- and nano-sized coal dust and methane–coal dust mixtures in a pipe

摘要

Coal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust. In order to study the impact of nano-sized coal on coal dust and methane–coal dust explosions, a pipe test apparatus was used to analyze the explosion pressure characteristics of five types of micro-nano particle dusts (800?nm, 1200?nm, 45?μm, 60?μm, and 75?μm) at five concentrations (100?g/m~(3), 250?g/m~(3), 500?g/m~(3), 750?g/m~(3), and 1000?g/m~(3)). The explosion pressure characteristics were closely related to the coal dust particle size and concentration. The maximum explosion pressure, maximum rate of pressure rise, and deflagration index for nano-sized coal dust were larger than for its micro-sized counterpart, indicating that a nano-sized coal dust explosion is more dangerous. The highest deflagration index K _( st )for coal dust was 13.97?MPa/(m·s), indicating weak explosibility. When 7% methane was added to the air, the maximum deflagration index K _( st )for methane–coal dust was 42.62??MPa/(m·s), indicating very strong explosibility. This indicates that adding methane to the coal dust mixture substantially increased the hazard grade.