Kinetics of pyrolysis of rice husk

The pyrolysis of rice husk in both grain and powder form was investigated to determine the kinetic parameters. Experiments under non-isothermal conditions were carried out for rice husk grain and powder samples in nitrogen, and for rice husk grain samples in carbon dioxide at heating rates of 5, 10, 25, 50 and 100°C/min. Experiments were also carried out with rice husk grain samples in nitrogen under isothermal conditions at temperatures 250, 275, 300, 350, 400, 450 and 500°C. From analysis of both the isothermal and non-isothermal data, it was found that pyrolysis proceeds in two distinct temperature zones with a transition at 350°C. The reaction orders were found to be 1.5 in the lower temperature zone and 2.0 in the higher temperature zone. The kinetic parameters obtained from isothermal experiments were found to be consistent with non-isothermal values. A method is proposed for determining the pyrolysis rates at any heating rate. The method was found to predict satisfactorily the pyrolysis data at different heating rates of rice husk.