Computational study of biomass fast pyrolysis in a fluidized bed reactor

Biofuels are considered a promising source of renewable energy. Pyrolysis uses heat in an inert atmosphere to break down biomass and produce biofuels like bio-oil (tar) and synthesis gas. This paper presents a computational study of fast biomass pyrolysis in a laboratory fluidized reactor. A laminar flow regime and an Eulerian-Eulerian approach were considered. A comprehensive kinetic model consisting of sixteen irreversible, first-order reactions was coupled with conservation equations of mass, momentum, and energy. The computational model was validated with data reported in the literature. The effect of biomass type and reactor temperature on the thermal decomposition of biomass were analyzed, finding a direct relationship between the content of cellulose and production of tar and similarly between the content of lignin and production of char. Also, the absence of lignin in the biomass dramatically changes the tar and gas compositions. Energy requirements, temperature contours, the composition of the exit gases, and final product yields (tar, char, and gas) are reported.