Reactivity in air, kinetic parameters and various ash properties were evaluated for wood and waste wood materials, and their mixtures with a high- and a low-rank coal. The obtained data should be useful for co-firing applications in existing and developing systems. Combustion experiments were carried out, for previously devolatilized samples, in a thermogravimetric analyser, over the temperature range of 25 to 850ºC, at a heating rate of 10ºC/min and with a material particle size of -250ým. The ashes were characterized by chemical, mineralogical and microscopical analyses, while slagging and fouling propensities were estimated through the use of empirical indices. Biomass chars were more reactive than coal chars. Bituminous coal was the least reactive material. The reactivity of the blends was greatly influenced by the rank of each coal and the proportion of each component in the blend. The kinetic parameters were determined by means of a power law model. Some interactions seemed to occur between the blend components during combustion, while the activation energies of the mixtures were somehow increased. The composition and fusibility of the ashes varied in proportion to the biomass content in the mixture. Blending of waste wood with lignite and wood with bituminous coal did not change substantially the slagging/fouling potential of lignite and bituminous coal, respectively.
Keywords: Biomass, Coal, Blends, Combustion