The core mechanism of the torrefaction lies in the selective removal of water and some light volatile components from biomass, while retaining as much as possible the solid skeleton structure and most of the carbon elements. Within this temperature range, hemicellulose in biomass undergoes significant decomposition first, producing a large amount of water, carbon dioxide, and light oxygen-containing organics; cellulose and lignin are relatively stable, mainly undergoing structural rearrangement and partial cross-linking reactions. This differentiated decomposition behavior results in pyrolysis products with a lower oxygen-to-carbon ratio, higher energy density, and better hydrophobic properties.

The pretreatment and positioning of torrefaction make it a key technical link connecting biomass raw materials with high value-added applications. Untreated biomass raw materials generally have inherent defects such as high moisture content, low energy density, poor grindability, and strong moisture absorption, which severely limit their large-scale application in the industrial field. Through torrefaction pretreatment, the moisture content of biomass can be reduced from 30-50% to less than 5%, the volumetric energy density can be increased by 30-50%, the grinding energy consumption can be reduced by 70-90%, and at the same time, it acquires hydrophobic characteristics similar to coal, greatly expanding its application range and economic value.