Ignition and propagation properties of coal dust – air – methane hybrid mixtures
In: Revue roumaine de chimie: Romanian journal of chemistry, Band 66, Heft 1, S. 25-32
The presence of a flammable gas in a combustible dust cloud significantly modifies its explosivity parameters. Thus, a hybrid mixture can become flammable even when both the dust-air and gas-air binary mixtures are under the corresponding lower explosion limits. The pressure-time histories of hybrid mixtures formed by coal dust, methane and air at different concentrations, at 1 bar initial pressure and normal temperature, were studied using the standard 20 L spherical explosion vessel and 5kJ chemical igniters or 10 J permanent sparks. From the early stages of the pressure-time history, when the pressure increase is equal to or less than the initial pressure, the normal burning velocities were evaluated and discussed.