Prediction and modeling of the basic properties of biomass after torrefaction pretreatment

摘要

Torrefaction is a promising and effective pretreatment technology to upgrade biomass into a more homogeneous and hydrophobic fuel with higher calorific value and energy density. The main objective of this study was to establish a torrefaction model to predict the basic properties (ultimate and proximate analysis, mass and energy yields) of torrefied biomass. Three groups of lignocellulosic biomass, namely woody biomass (Chinese fir), herbaceous biomass (corn stalk), and shell-like biomass (palm kernel shell), were used as raw material to establish the model. First, the simulation process was carried out on the entire torrefaction stage (200-300 degrees C) based on the linear fitting method. Then, in order to obtain a more accurate model, the model was established by using two-stage torrefaction process (mild stage with 200-250 degrees C and severe stage with 250-300 degrees C) and the quadratic equation. Further, the model was validated based on the torrefaction results from literature reports by using the analysis of variance. Result showed that the values of statistical parameters (relative error and mean absolute error) were less than 5%. This indicated that the simulated two-stage torrefaction model obtained by using the quadratic equation can, in general, aid in providing prediction of basic properties of woody torrefied biomass with higher accuracy. This study is helpful for the design of large scale torrefaction equipment and optimization of the torrefaction process.