Combustion reaction mechanism of four typical Chinese biomass by TG and DTG

Abstract

The combustion reaction mechanisms of Rape stalk, Cotton stalk, Rice straw and Manyflower Silvergrass produced in China were investigated combining the methods of thermogravimetry (TG) and differential thermogravimetry (DTG) in this paper. Experiment was conducted in a TG-DTA analyzer, volume fraction of reaction atmosphere was N 2:O 2 = 80:20 and heating rate was 30°C min -1. The temperature ranges of two main reaction phases were identified by analyzing TG and DTG curves. Coats-Redfern method was employed to calculate kinetic parameters (activation energy, pre-exponential factor and order of reaction). The activation energies of volatile combustion phase and fixed carbon combustion phase were in the range of 11-35.8 kJ mol -1 and 118.4-181 kJ mol -1, respectively. Results showed that the reaction of two phases could be described by zero order and two order functions. The activation energies obtained in the second reaction zone were relatively higher than those of the first reaction zone. The pre-exponential factors ranged as high as 35.8125 min -1 in the first reaction zone and 2.8071 × 10 13 min -1 in the second reaction zone. The reaction initial temperatures of four samples ranged from 430 to 460 K and reaction final temperatures ranged from 740 to 810 K. Temperature ranges and some reaction kinetic parameters were a little different of four samples, due to the different content of samples. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.