Fast pyrolysis multiphase CFD-kinetics model in a drop tube reactor

Abstract

Experimental investigation of biomass pyrolysis kinetics is challenging due to simultaneous complex chemical reactions, interphase heat and mass transfer. A CFD model and simulation overcome the challenges faced in experimental work and provides a detailed characterization of pyrolysis kinetics. In this work, a granular multiphase flow model with 17 heterogeneous reactions, 53 interphase mass transfer, and 35 pyrolysis species and Nitrogen (36 species) transport models was implemented to investigate the pyrolysis kinetics using a continuous flow drop tube reactor (DTR). The model predicted that 45 wt% biofuel, 25 wt. % permanent gases, 10 wt% water and 20 wt% biochar is produced from a biomass feedstock at a reactor wall temperature of 773 K. The majority of biofuel (35 wt%) is produced from cellulose. While hemicellulose and lignin mainly produce permanent gases (16 wt%) and biochar (8 wt%), respectively. Product characterization and visualization of the pyrolysis process in a virtual environment mimicking the actual reactor in real-time sheds light on the pyrolysis reaction processes lacking in the literature.