Dynamic modeling and scenario analysis of a 2 MWth circulating fluidized bed gasifier

• Dynamic APROS model of a 2 M W t h CFB gasifier with core-annulus hydrodynamics and staged agent injection. • Model validated against BFB experimental data with strong agreement in temperature, pressure, and syngas composition. • Systematic dynamic analysis of CFB gasifier behavior under realistic part-load and market-driven conditions. • CFB gasification demonstrated as a flexible, reliable technology suitable for renewable-integrated energy systems. The expansion of variable renewable energy sources increases the demand for conversion technologies capable of flexible operation. Circulating Fluidized Bed (CFB) gasifiers offer strong potential due to their thermal stability, high throughput capacity, and fuel flexibility. However, their dynamic behaviour under varying operating conditions remains insufficiently characterized. This study develops a dynamic model of a 2 M W t h CFB gasifier using the APROS simulation platform and evaluates its performance across a range of steady and transient operating scenarios. Three categories of simulations are considered: (1) steady-state operation at multiple thermal loads (100%, 80%, 60%, and 40%), (2) controlled dynamic transitions including ramp-down and ramp-up sequences, and (3) a market-based scenario derived from real excess electricity data from the Finnish power grid. Key performance indicators—including riser temperature distribution, gas velocity, pressure drop, and syngas composition—are examined to assess thermal and chemical stability. The results demonstrate that the gasifier maintains stable operation under most dynamic conditions within the circulating regime. At lower loads, where fluidization shifts toward bubbling behavior, reductions in syngas yield and more pronounced thermal gradients occur due to decreased solids circulation and heat transfer. Despite these changes, the system shows strong recovery capability and sustains acceptable syngas quality. Overall, the findings confirm that the APROS-based model can reliably capture the time-dependent behaviour of fluidized bed gasifiers and underscore the suitability of CFB gasification for integration into flexible, renewable-driven energy systems.