(513i) Dynamic Thermogravimetric Studies of Woody and Herbaceous Biomass

Reactor design, e.g. a combustor, greatly depends on characterization of fuels and understanding the kinetic relations at process conditions. This study steps beyond the fundamental methods of thermogravimetry to modulated (MTGA) and Hi-Res techniques to (1) add characterization detail and (2) increase the utility of thermal analysis data. Modulated TGA methods overlay sinusoidal functions on the heating rates to calculate activation energy as a function of process temperature. Under devolatilization conditions, Hi-Res TGA maintains a constant rate loss and caries temperature accordingly. These two methods, run either independently or overlaid, offer a great deal more than traditional thermogravimetric rate analysis in which multiple samples at different heating rates are run to different final temperatures. Advanced methods will allow researchers to use less sample by conducting fewer runs, target designs of experiments, and quantify error more easily.

The parameters of the studies included here vary heating rate at 10, 30, and 50 ℃/min; vary gas-phase oxygen for pyrolysis or combustion conditions; and particle size ranges of 100-125 µm, 400-425 µm, and 600-630 µm. The two biomass fuels used in the studies are pinewood from Northern Sweden and wheat straw. The influence of pretreatment, or torrefaction, is also included at temperatures of 220, 250, and 280 ℃. Results show the dependence of these parameters upon one another from a traditional thermal analysis approach as well as MTGA and Hi-Res thermogravimetric investigations to show future directions for thermal analysis techniques.