CFD and experimental studies on a circulating fluidised bed reactor for biomass gasification

Biomass gasification has been extensively studied in different thermochemical systems, as has the potential to produce fuel gas for chemicals, fuel and electricity applications. Circulating fluidised bed systems (CFB) are of particular interest due to the high reaction rates and thermal efficiency. The study of varying particle properties and gas velocities during the solids recirculation in a CFB system has been proved to greatly influence the overall biomass gasification process. A comparison between experimental and modelling gas-solid interactions can represent a comprehensive and analytical approach for further understanding and scaling up this reaction system. However, running several experiments is expensive and time-consuming. In this work, a reliable and accurate computational fluid dynamics (CFD) framework has been developed to evaluate the hydrodynamics performance of a CFB gasifier. The multiphase CFD model was validated using a pilot-scale CFB gasifier and silica sand. The CFD and experimental data showed good agreement for the solid recirculation tests, for example when comparing predicted and measured the spatial distribution of pressure up the gasifier's riser. It is the first time that the spatial distribution of solids around a CFB system has been numerically predicted, which can provide guidance to evaluate the hydrodynamics performance of CFB.