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 O-2/CO2 mixtures with O-2 mole fractions ranging from 21% to 50%. Experimental results reveal that the crossing point temperature (CPT) decreases with increasing O-2 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. (C) 2017 Elsevier Ltd. All rights reserved.