Property of drying, pyrolysis, gasification, and combustion tested by a micro fluidized bed reaction analyzer for adapting to the biomass two-stage gasification process

Abstract

In the present research, a concept of fluidized bed two-stage gasification has been proposed to gasify the wet industrial biomass, which decouples the direct gasification of biomass into the main sub-processes of drying, pyrolysis, gasification, and combustion. To better understand the reaction behavior and kinetics of these main sub-processes, a micro fluidized bed reaction analyzer was adopted. Moreover, a kind of water-adsorbing char was chosen to simulate the drying behavior of wet biomass. In the examined temperature range of 1123–1223 K, the processes of pyrolysis and combustion were conducted in the second scale, while that of gasification and drying was in the minute level, dominating the whole gasification process. For the reaction rate, at above 1173 K, they followed the order of pyrolysis > combustion > gasification > drying. The volume reaction model and shrinking core reaction model can be used to describe the process of pyrolysis/gasification and drying/combustion, respectively. For pyrolysis, combustion, drying, and gasification, the calculated activation energies were about 29.51, 62.39, 83.75, 210.23 kJ/mol, respectively. Finally, a schematic diagram of the FBTS gasification process was proposed for treating the wet Chinese distilled grains according to the reaction behavior and kinetics.