Gasification Kinetics of Organic Solid Waste Pellets: Comparative Study Using Distributed Activation Energy Model and Coats–Redfern Method

The gasification kinetics of pellets obtained from organic solid wastes (OWS) and raw materials were studied using the Coats–Redfern and DAEM methods. The different methods were comparatively analyzed for mutual verification, and the similar activation energies obtained by each method affirmed the accuracy of the kinetics calculation. Overall, the activation energies of the char gasification stage ranged from 200 to 265 kJ mol−1, higher than those of the devolatilization stage, which ranged from 130 to 200 kJ mol−1 for all pellets and raw materials. During the devolatilization stage, the activation energies of the pellets were invariably higher than those of their corresponding raw materials, which was the opposite for the char gasification stage. A detailed comparison between the calculation results from the Coats–Redfern and DAEM methods confirmed that the devolatilization stage is controlled by one-dimensional diffusion, and the gasification stage is controlled by two-dimensional or three-dimensional diffusion for pellets and raw materials.