Gasifier-torrefier using syngas as the thermal agent

Torrefaction is known as mild pyrolysis process occurring at temperature range of 200-300 °C. Torrefied biomass can be co-fired directly with coal in boilers without any fuel pre-treatment, thus, increasing its economic value over raw biomass significantly. An experimental rig was developed to characterize the torrefaction process of wood pellets in a new gasifier-torrefier. Temperature of the syngas exiting the gasifier is about 300-400 °C which is sufficient for biomass torrefaction. Biomass torrefaction process is fully characterized based on biomass bed height and temperature, residence time and heating value of the torrefied product. Temperature profiles inside the torrefaction reactor were recorded for different air flow rates of 9, 12, 15 and 18 m3/h. The process has achieved about 10-40% and 5% enhancement in heating value of torrefied biomass and syngas respectively.