Explosive property and combustion kinetics of grain dust with different particle sizes

The effect of particle size on the combustion and explosion properties of grain dust is investigated by Hartmann tube, cone calorimeter (CC), and thermogravimetry (TG), it aims to provide fundamental experimental data of grain dust for an in-depth study on its potential risk. The fine-grain dust facilitates the decrease in the minimum ignition temperature (MIT) of dust layer and dust cloud, as well as the obvious increases in the maximum explosion pressure P(max) (climbs from 0.36 to 0.49 MPa) and pressure rising rate dP/dt (rises from 6.05 to 12.12 MPa s(−1)), leading to the increases in maximum combustion rate (dw/dτ)(max) and combustion characteristic index S, corresponding to the greater or severer potential risk. Because the E corresponding to combustion increases from 106.05 (sample with a particle size of 180–1250 μm) to 153.45 kJ mol(−1) for the sample of 80–96 μm, the combustion process gradually transforms from diffusion-controlled into a kinetically controlled mode with the decreasing particle size of grain dust, together with the retardation of initially transient charring. It determines that the competition between the charring and combustion dominates the decomposition, and the combustion prevails for the coarse particle, while the charring controls the combustion for the fine-grain dust.