A detailed general model of the gasification zone of a dual fluidised bed gasifier

Biomass gasification has proved to be a promising method of producing renewable gases. Modelling biomass gasification is instrumental in designing and optimising a biomass-based gas production plant. The current paper proposes a general semi-kinetic model of steam and air/steam gasification of solid biomass. Given the range of technologies available, the focal point of this study was to provide a detailed guide for the simulation of the gasification zone of a dual fluidised bed (DFB) gasifier. The study introduces a numerical procedure to estimate char and tar yields and compositions. Tar conversion via thermal cracking and steam reforming mechanisms were modelled using a semi-empirical approach. Simulation results, namely product gas composition, mass flow rate, and tar concentration, were validated against experimental data for the gasification zone of three DFB gasifiers with reasonable accuracy. This agreement demonstrated the robustness of the model to analyse a similar technology or in developing a new one. Aspen Plus, as a standard simulation software package, was employed to implement the model.