Predicting the biomass conversion performance in a fluidized bed reactor using isoconversional model‐free method

Abstract

The first objective of this study to analyze the detailed pyrolysis kinetics of four Canadian feedstocks through two techniques: thermogravimetric analysis (TGA) using the isoconversional model‐free method; and fast pyrolysis in a fluidized bed reactor using the simple Arrhenius model. The four biomass feedstocks were pyrolyzed in a fluidized bed reactor at 400–520 °C. The experiments were conducted for three size fractions. The thermogravimetric analysis was performed at four heating rates (2, 5, 10, and 15 °C/min) in an inert atmosphere. TGA experiments showed that the decomposition rate of agricultural residues was significantly lower than woody biomass due to high volatiles and low ash content in the latter. The range of average activation energy from fluidized bed experiments was 150–168 kJ/mol and 160–180 kJ/mol from TGA experiments. The difference is attributed to different methodology in the experiments and the determination of kinetic parameters. The second objective was to apply the global kinetic parameters from the TGA to predict the decomposition of biomass to biochar and to compare it with the experimental biochar left in the fluidized bed reactor at different temperatures. This study also confirmed that at high temperatures for all the feedstocks, average kinetics parameters obtained from the TGA could produce fluidized bed biomass conversion results with an average variation of 4 %.