HEAT-TRANSFER AND KINETICS OF LIGNITE DEVOLATILIZATION IN WIRE-MESH APPARATUS

A model of lignite devolatilization in a wire-mesh apparatus is propos ed in this paper. The model couples the heat transfer between grid and particle with a multiple-reaction kinetic model. The kinetic paramete rs are derived from the experiments, in which two Chinese lignites are devolatized. The model predictions of heating-rate and particle-size dependence of particle temperature, devolatilization rate and weight l oss are presented. An index is suggested to assess the cumulative effe ct of heat transfer limitation on devolatilization. The model reveals that under a typical condition (particle size 50 mum, heating rate < 1 000-degrees-C s-1), the heat transfer limitation could be negligible. However, with further increasing particle size and heating rate, the h eat transfer limitation seems to become somewhat important.