Kinetic studies of dehydration, pyrolysis and combustion of paper sludge

The reaction kinetics of drying, pyrolysis and combustion of paper sludge have been determined in a thermogravimetric analyzer (TGA). The effects of heating rate (5–30 K min−1) and sample weight (10–50 mg) on drying and pyrolysis of paper sludge have been determined. The kinetic parameters of char combustion are determined at the isothermal conditions (723–1173 K). For dehydration, pyrolysis and combustion of paper sludge, temperature can be divided into drying (−470 K), pyrolysis [low (470–660 K), medium (660–855 K)] and combustion (>855 K) ranges. From the kinetic parameters (frequency factor and activation energy) of water decomposition, two major degradable compounds are found and the experimental thermogravimetric curves predicted by those parameters. For char combustion, the reaction order is found to be unity. The char combustion is well expressed by the shrinking core model with chemical reaction controlling and the activation energy is changed from 24.3 to 10.14 kJ mol−1 K−1 at 873 K.