Effect of heating rate on the thermal properties and devolatilisation of coal

The apparent specific heat of coal was measured by employing a computational calorimetric technique during continuous pyrolysis at heating rates of 10, 25 and 100°C min^-1. For all of the examined heating rates, the apparent specific heat was found to be approximately 1.4 kJ kg ^-1 K^-1 at room temperature. When the sample reached decomposition temperature (∼410°C), the specific heat increased to 1.9 kJ kg^-1 K^-1. From this point, the apparent specific heat was greatly influenced by the coal reaction mechanism. For this purpose a detailed gas analysis was carried out for the three examined heating rates. It was found that with increased heating rates, the devolatilisation reactions were shifted to higher temperatures, as reflected in the measured apparent specific heat.