Production of Coal-Like Solid Fuel from Albizia Chinensis Sawdust via Wet Torrefaction Process

Albizia Chinensis is a plant easily found in Indonesia and other South East Asian countries. The sawdust from this plant is a lignocellulosic waste that can be potentially upgraded for the fuel purposes. This research investigated the potential of upgrading sawdust into a coal-like solid for fuel by a wet torrefaction process. In this project, a 1 L torrefaction reactor with an electric heater was employed to perform the carbonization of the Albizia chinensis sawdust. Wet torrefaction was performed in batch at temperatures of 190–230°C with holding times of 20°C, 30 and 60 min. The solid to water ratios of 1:3, 1:5 and 1:10 were used. The results showed that the chemical and physical properties of sawdust and hydrochar varied as a function of reaction temperature, holding time and solid load. The results also suggested that wet torrefaction could increase the fixed carbon in sawdust while the ash content and volatile matter decreased. The high heating value of hydrochar was 24.55 MJ/kg higher than raw sawdust, 18 MJ/kg. CO2 was predominantly detected in the gas phase, reaching the of >90% CO2. The liquid products were identified as sugar and organic acid compounds, which may be desirable feedstock for biochemical production.