Combustion properties of torrefied biomass obtained from flue gas-enhanced reactor

Torrefaction is the process of thermal treatment that leads to enhanced biomass properties. Specifically, torrefaction of raw biomass can lead to higher energy density, improvement of handling and grinding properties, and other advantages. This work investigates the combustion properties of torrefied biomass obtained from the torrefaction of willow (Salix viminalis) in the presence of flue gas. The properties were compared with other solid fossil fuels such as Polish hard coal and Polish lignite. The comparison was based on proximate and ultimate analyses as well as the combustion of the fuels using an auto-thermal bubbling fluidized bed reactor. The combustion process of torrefied willow was stable, and the most promising result was radically low SO2 emission levels. However, the relatively high NOx emission should be decreased by the application of primary or secondary methods of NOx removal.