Reactor network modelling for biomass-fueled chemical-looping gasification and combustion processes

A reactor network was developed to predict the performance of biomass-fueled chemical-looping gasification (CLG) and chemical-looping combustion (CLC) in packed beds. The reactor network consists of a combination of continuous stirred-tank reactors, plug flow reactors, and packed bed reactor zones. The model was developed and validated using experimental data under both CLG and CLC conditions, as well as a sensitivity analysis. Using the validated model, a variety of oxygen carrier (OC) bed lengths and locations were assessed to determine the resulting impact on the CLG and CLC performance. For CLG, the highest gasification efficiency (75.1%) occurred with an OC/biomass ratio of 0.25 combined with a steam/biomass ratio of 1, with the OC placed near the reactor inlet. The resulting gasification efficiency was of similar magnitude to that reported in experimental data. For CLC, a fully packed bed with steam as the inlet gas resulted in the highest outlet CO2 fraction, with an outlet stream that consisted of 95% CO2 and H2O. This reactor design improved the outlet CO2 purity by an order of magnitude in comparison with experimental data; thus demonstrating their potential and advancing the commercial adoption of these emerging technologies. The model was also used to predict the dynamic behaviour of the system and to determine the most suitable time to end the reduction stage, while maintaining a high CO2 fraction in the recovered gas. These design strategies can be implemented to facilitate biomass-fueled energy generation by improving the sustainability of the gasification and combustion systems.