Characteristics of coal dust deflagration under the atmosphere of methane and their inhibition by coal ash

To investigate the flame propagation of coal dust deflagration and the inhibition characteristics of coal ash which as a mixed inert powder under the atmosphere of methane. A vertical combustion pipe with half-open was built to study the methane/coal dust deflagration at different concentrations of coal dust and different mass fractions of coal ash. The residues after coal dust deflagration were characterized by SEM, XPS and FTIR. Results indicate that the deflagration intensity of coal dust firstly increases and then decreases with the increasing of coal dust concentration. Under this experimental conditions with 7 vol% methane/air, the optimum deflagration phenomenon appears at the dust concentration of 200 g/m3. After the addtion of coal ash, the decomposition of coal dust was prevented to some extent for its heat resistance and absorption. The intensity of methane/coal dust deflagration was weakened with the increasing of coal ash mass fraction. In addition, the inhibition mechanisms of coal ash on coal dust deflagration were summarized based on the material analysis of the deflagration residues.