Quantifying the Heats of Coal Devolatilisation

摘要

An experimental apparatus was developed to measure the thermal properties of coal in order to determine the heats of reactions during devolatilisation. The coal samples were typically heated at a rate of 10℃/min to a maximum temperature of 1000℃. Measuring the temperature changes at two selected locations within the sample allowed the calculation of the apparent specific heat and thermal conductivity by employing an inverse numerical technique to solve the heat conduction equation. The results showed significant differences between thermal and coking coals within the temperature range of thermal decomposition. The reactions for the coking coals were predominantly exothermic while the thermal coals showed endothermic secondary reactions as well as exothermic reactions in the regions of re-solidification and contraction within the carbon planes. The enthalpies and activation energies for the individual reactions were subsequently extracted from the apparent specific heat data. The effects of heating rate within the range of 5 - 100℃/min were also examined.