Flue gas torrefaction of distilled spirit lees and the effects on the combustion and nitrogen oxide emission

Flue gas torrefaction (FGT) integrated with combustion was introduced for the clean treatment of distilled spirit lees (DSL). The effects of temperature, residence time, and volumetric flow rate of FGTs were investigated. The improvement in the physicochemical and combustion characteristics of the torrefied DSL and the reaction mechanisms were clarified by a tube furnace and the TG-MS device. The results showed that FGT could effectively improve the properties of DSL. With increasing temperature, residence time, and volumetric flow rate, the mass and energy yields decreased. FGT showed positive effects on the removal of free and bonding water, as well as the enrichment of lignin. FGT effectively inhibited the release of NOx. The overall emission of NOx was reduced by 57.3%. Additionally, the cost of DSL drying and denitrification could be greatly reduced by FGT. This study provided a practical treatment for DSL and new insight into FGT.