Heat transfer in pyrolysis of biomass particles with ash content

This study investigates the influence of ash content on heat transfer during biomass pyrolysis. Lumped capacitance and thermally thin particle models were used to predict the thermal behavior of biomass particles in a furnace, and results were compared with measurements from a thermogravimetric system (TGA). In the lumped capacitance model, the biomass particle is assumed to behave as a thermally uniform body subject to radiative heating in the furnace. The predictive model establishes three heating stages, including the initial heating stage (dehydration), pyrolysis, and the post-pyrolysis stage. Empirical correlations were developed to account for the effects of biomass biochemical composition and the heating rate on the decomposition process. This study addresses a key knowledge gap by incorporating the thermal effects of ash content into predictive models using its effective thermophysical properties. The results indicate that particle size, ash content, and heating rate significantly affect the pyrolysis characteristics, including pyrolysis temperature, particle conversion, and reaction duration. The effect of K 2 CO 3 was observed through a shift in the pyrolysis temperature and a reduction in the pyrolysis initiation time at higher heating rates. Overall, these findings highlight the importance of accounting for ash in biomass pyrolysis and provide new insights into the ash effect on temperature profiles, pyrolysis time, and conversion behavior.