Devolatilization and combustion kinetics of low-rank coal blends from dynamic measurements

The aim of this work was to investigate the devolatilization and combustion behavior of some low-rank coals and their blends to gather data useful for the development of the coprocessing of these fuels. Nonisothermal thermogravimetry experiments were carried out in inert and air atmospheres, over the temperature range of 25-850 degreesC, at a heating rate of 20 degreesC/min, and with a material particle size of -100 mum. Four blending ratios were used. The samples presented similar thermochemical reactivities. The differential thermogravimetric data for devolatilization. were fitted successfully to an independent, first-order parallel reactions model, while those for combustion were fitted to a power law model. Blending did not cause any significant interactions during devolatilization in the solid phase, so that the thermal conversion of blends could be sufficiently predicted based on the thermogravimetric data of the individual fuels. However, this was not true in the case of char combustion.