Comparison between equilibrium and kinetic models with Aspen Plus for a full scale biomass downdraft gasifier

The development of mathematical simulation models is an important tool in order to provide more accurate qualitative and quantitative information on biomass gasification process and the effect of process parameters. The modelling of the gasification process can be generally executed adopting one of the following approach: steady state models (equilibrium models), transient state models (kinetic models) and models based on the computational fluid dynamics. This paper shows a comparison between an equilibrium model and a kinetic one, applied to a full-scale woody biomass downdraft gasification plant using Aspen Plus® as simulation platform. The simulation results have been validated using those obtained during an extensive experimental activity, where the temperature profile within the reactor and gasifying air/syngas operative features are continuously measured. The kinetic model assures a reliable estimation of the hydrogen and methane concentration in the syngas, compared with the equilibrium model.