Non-isothermal thermogravimetric analysis of plywood wastes under N2, CO2 and O2 atmospheres

The rates of (1) devolatilisation, (2) char combustion and (3) char gasification with CO2 of plywood sawdust (Australian Standard 2207 'Interior Grade') was measured using non-isothermal thermogravimetric analysis (TGA). The influence of heating, rate 5, 10, 20, 50 and 100 degrees C/min) and reaction atmosphere (N-2, Air, CO2) was investigated. Irrespective of the reaction atmosphere. devolatilisation typically occurred at the same rate. Weight loss attributed to char oxidation was observed at temperatures >400 degrees C. while weight loss due to CO, gasification of char was observed at temperatures >800 degrees C. There was Uncertainty about the fate of some of the constituents of the plywood sawdust. i.e. urea-formaldehyde binders, which could not be fully evaluated using a TGA system without evolved-gas analysis. These components appeared to volatilise around 380 degrees C Oil the differential mass loss profiles in the presence of N-2 and CO2 and around 490 degrees C in the presence of air. A simple first-order reaction model was Used to interpret the experimental observations. The kinetic parameters for the main components of plywood sawdust were consistent with those reported previously for other biomass materials. This information is potentially useful for the design Of large-scale equipment to recover energy from discarded wood wastes. (C) 2008 Curtin University of Technology and John Wiley & Sons, Ltd.