Characterization of solid and liquid products from bamboo torrefaction

Solid and liquid products from bamboo (Bambusa sinospinosa) torrefaction were analyzed in the present study. Three different torrefaction temperatures of 250, 300, and 350 °C and three torrefaction durations of 30, 60, and 90 min are taken into consideration. The properties of both solid and liquid products are sensitive to the torrefaction temperature, whereas the influence of duration is relatively slight. Among the torrefaction temperatures of 250, 300, and 350 °C, 300 °C is recommended for upgrading bamboo in that it gives a more appropriate operation to enhance the higher heating value of the biomass while the solid yield is not too low. In the liquid products or condensable liquids, acids, alcohols, ketones, phenols, aldehydes, esters, etc. are detected. The contents of acids and alcohols in the liquids are richer, and acid formation is especially significant at the torrefaction temperature of 250 °C. The pH value of the condensable liquid is in the range of 2.27 and 2.60 which is close to that of bio-oil. The water content in the liquid product is around 50% and an increase in torrefaction temperature lowers the content. After undergoing dewatering, the calorific value of the liquid product is enlarged in a significant way. The results show that dewatering is an important process to upgrade the liquid product as a fuel.