Pressurized gasification of torrefied woody biomass in a lab scale fluidized bed

This work reports experimental results concerning the influence of torrefaction level and pressure on product yields and composition during fluidized bed O2/steam gasification of two different raw biomasses. The results show an increase in gas yield with pressure and torrefaction level for both types of biomass considered. Increasing pressure caused the produced gas composition to shift towards higher CH4 and CO2 content, while H2 and CO levels decreased. The effect of the type of original biomass on gas composition was limited, and became less relevant as pressure and torrefaction level increased. The analysis of the tars produced during gasification also revealed that higher pressures led to the increase of tar yields. On the other hand, torrefaction level presented the opposite effect, with lower tar yields and lighter molecular weight distribution of tars as torrefaction level increased. Since torrefaction is being considered as a promising pretreatment technique for upgrading biomass to a higher quality solid fuel more suitable for the integration of gasification into biofuels production, the results from this study are relevant for evaluating the influence of the level of torrefaction on the performance of gasification under typical operating conditions in practical applications.