Biomass residues in the Mediterranean region come mainly from agricultural and agro-industrial activities and forest by-products. The paper presents the results of Kinetic parameters and main devolatilization characteristics of three biomass materials, when these are used either alone or in conjunction with Greek lignite. Namely, olive kernel forest, and cotton residues were pyrolysed in a thermo gravimetric analyser, under dynamic conditions. The effect of material particle size and heating rate was investigated both on the Pyrolysis behaviour and reaction Kinetics, over the temperature range of 25-850 oC. Furthermore, experiments with blends of lignite and biomass were conducted under the same conditions at the lower heating rate. The biomass materials presented higher thermo chemical reactivity than lignite. Their decomposition was successfully modelled by three first-order independent parallel reactions, describing the degradation of hemicellulose, cellulose and lignin. No significant influence of the particle size was detected, both on the devolatilization characteristics and Kinetics. The effect of the heating rate on the Pyrolysis behaviour was more pronounced for biomass materials rather than lignite. A comparison between slow and fast heating rate tests reveals a small displacement of the DTG profiles to higher temperatures. It was concluded that such ‘solid bio-fuels’ could support the combustion of poor coals, because of the faster and in much higher quantity release of volatile compounds.
Keywords : Biomass, Devolatilization, Kinetics