Effectiveness of thermodynamic adaptative equilibrium models for modeling the pyrolysis process

The pyrolysis process of biomass is one of the innovative actions for delivering sustainable energies. The research carried out introduces two thermodynamic equilibrium models (TEMs), called PyRO_2 and PyRO_3, developed for simulating pyrolysis process of biomass. This study typology constitutes tricky task since it involves a large number of physical and chemical transformations and produces several species. Particularly, it is difficult to obtain the simultaneous and trustworthy estimation of the bio-oil yield and combustible gases (CO, H2 and CH4) through TEM, on considering the presence of elementary hydrogen and carbon in the bio-oil chemical formula. Thereby, the mathematical models need to be preliminarily “tuned” for the specific pyrolysis process in order to achieve reliable results. In this study two pyrolysis processes, low and intermediate, were carried out on different biomasses, to test the effectiveness of the models. The comparison among simulations and experimental data indicates that the yields of released volatiles, the lower heating value (LHV), as well the bio-oil yield can be predicted with a reasonable accuracy under various operating conditions. In particular, a decrease of the bio-oil yield has been detected with the rise of the process temperature, in agreement with the thermal cracking of gases and vapors.