A system-level dynamic model for gasification process: Steady-state experimental validation and load-change predictions

The expansion of variable renewables creates a need for conversion technologies that can operate flexibly. Bubbling Fluidized Bed (BFB) gasifiers are promising because of their thermal stability and fuel flexibility, yet their dynamic behaviour is poorly characterized. This study develops one of the first system-level dynamic model of a 450 kWth BFB gasifier using the APROS dynamic simulation platform, which natively couples thermal-hydraulics, gas-solid interactions, and control logic for time-domain studies. The model, based on the pilot facility at the Technical University of Darmstadt, is validated against experimental steady-state measurements of riser temperature, pressure distribution, and product gas composition. Predictions show strong agreement, with temperature and pressure errors below 8 % and 2 %, respectively. Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) values for temperature and pressure are also low (<3 %). Despite employing simplified reaction kinetics, the model reproduces major product gas species with sufficient accuracy for energy system evaluation. The model is then applied to investigate part-load steady states and dynamic load transitions. Simulations demonstrate that the gasifier maintains stable hydrodynamics and syngas composition during load reductions and ramp-ups, with only moderate fluctuations in CO and H2 (CO≈14−18%, H2≈10−12%). These findings establish one of the first credible dynamic frameworks for BFB gasification, offering testable predictions to support pilot-scale transient measurements, control design, and integration of gasification technologies into renewable-based hybrid energy systems.