Predicting the rapid devolatilization of diverse forms of biomass with bio-FLASHCHAIN

This paper introduces a new reaction model for the rapid devolatilization of diverse forms of biomass called bio-FLASHCHAIN (bio-FC). Given the proximate and ultimate anal)ses and the thermal history and pressure, bio-FC predicts the complete distribution of primary devolatilization products from paper and any form of wood, grass, and agricultural residue, including the yields of tar and all major gas species, the elemental compositions of tars and chars, and the molecular weight distribution of tar. Biomass is represented as a chain copolymer of cellulose and a lignin-like component. The actual composition and structure of cellulose are implemented, whereas the composition of the lignin-like component is assigned from the ultimate analysis of the whole biomass. The reaction scheme is based on the depolymerization of a mixture of chain macromolecules into fragments that volatilize into tar, partially decompose into gases, or recombine with the nascent char matrix. Comparisons to measurements demonstrate that bio-FC is a macromolecular reaction framework that can represent the complete distribution of primary devolatilization products from biomass. They also suggest that the model predictions will express the impact of variations in the most important operating conditions. The novel calibration procedure for the impact of mineral catalysis does not incorporate detailed mineralogical analyses or measured product yields. But many more evaluations are necessary to establish that it is suitable for the complete range of biomass fuel properties.