The flame deflagration of hybrid methane coal dusts in a large-scale detonation tube (LSDT)

To gain a deeper understanding for the influences of coal dust on methane flame deflagrations in chemical plants, a LSDT has been established at the University of Newcastle, Australia. The initial ignition source was delivered by the ignition of 50 mJ chemical ignitors. This study focuses on the influences of dilute coal dust concentrations (below 30 g m−3) on the deflagration of methane in a hybrid form. The work addressed the characteristic of hybrid flame deflagration behaviour including the flame velocity, pressure profile, dynamic and static pressure. Two concentrations of coal dust were introduced to the methane deflagrations, which were 10 g m−3 and 30 g m−3. The results revealed that the presence of a diluted coal dust of 10 g m−3 significantly enhanced the flame travelling distance of a 5% methane concentration, from 12.5 m to 20.5 m. Introducing a 30 g m−3 coal dust concentration also enhanced the flame travelling distance of a 5% methane concentration, from 12.5 m to the EDT (End of Detonation Tube, 28.5 m). This enhancement was associated with boosting the flame velocity and the over pressure rise. For a higher methane concentration (i.e., a 7.5% methane concentration), the flame of the methane reached the EDT. Introducing 10 g m−3 coal dust to a 7.5% methane explosion increased the flame intensity signal, from 1 V to the maximum reading value (10.2 V), and enhanced the flame velocity at the EDT by about 14 m s−1 and finally, increased the stagnation pressure at the end of the detonation tube from 1.25 bar to 4.6 bar.