Combustion characteristics of unburned pulverized coal and its reaction kinetics with CO₂

The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms between UPC and CO₂ in an isothermal experiment in the temperature range 1000-1100℃ were investigated. The combustion performance of unburned pulverized coal made from bituminous coal (BUPC) was better than that of unburned pulverized coal made from anthracite (AUPC). The combustion characteristic indexes (S) of BUPC and AUPC are 0.47×10^-6 and 0.34×10^-6%2·min^-2·℃^-3, respectively, and the combustion reaction apparent activation energies are 91.94 and 102.63 kJ·mol^-1, respectively. The reaction mechanism of BUPC with CO₂ is random nucleation and growth, and the apparent activation energy is 96.24 kJ·mol^-1. By contrast, the reaction mechanism of AUPC with CO₂ follows the shrinkage spherical function model and the apparent activation energy is 133.55 kJ·mol^-1.