Self-heating characteristics of coal dust deposits by a hot gas flow in oxy-fuel atmospheres

Grewer oven tests with a constant heating rate are conducted to investigate the self-heating characteristics of coal dusts under air and O2/CO2 mixtures with O2 mole fractions ranging from 21% to 50%. Experimental results reveal that the crossing point temperature (CPT) decreases with increasing O2 mole fraction and coal maturity. The inhibiting effect of CO2 is found to be comparatively small for the self-heating process. In addition, a numerical method is developed to study the self-heating behaviour of coal dusts with an emphasis on the roles of moisture content, gas conditions, mass flow and heating rate. The kinetic parameters are estimated by a modified 2nd-order kinetic steady-state CPT method. The computational CPTs related to gas atmospheres show a good agreement with experimental results. Parameter analysis shows that the heating rate has a comparatively pronounced effect on CPTs compared to moisture content and gas flow rate.