Modeling and comparative analysis of metallic fuels combustion in a fluidized bed power plant

Abstract

Reactive solid fuels are being studied as possible carbon-free energy carriers for future thermal power systems. This thesis evaluates the feasibility and performance of selected metallic fuels in a CFB power plant under constant operating conditions. The analysis is based on a validated commercial-scale 90 MWth CFB power plant model. Steady-state thermodynamic simulations were performed using EBSILON Professional, in which the original coal fuel was replaced by aluminum, magnesium, titanium, calcium, and zinc. The plant configuration, system boundaries, and operating conditions were kept unchanged for all cases. The fuel and air flow rates were adjusted to maintain the same thermal input, allowing a consistent comparison under identical operating conditions. The results show that all investigated metallic fuels can operate within the same plant framework, although clear differences are observed in air demand, flue-gas flow, oxide formation, and overall efficiency. Aluminum and titanium achieve the highest electrical performance because of their favorable balance between effective heat release and oxidizer demand. Magnesium and calcium show slightly lower but still relatively stable performance, while zinc results in lower efficiency because of its significantly higher fuel and air flow requirements. The analysis demonstrates that metallic fuel performance cannot be evaluated only through thermochemical properties. Gas-side flow behavior, oxide formation, solids circulation, and solids handling also strongly influence the overall system response. Overall, the simulation results provide a consistent basis for comparing metallic fuels in CFB systems and highlight the importance of further research on material behavior and practical implementation under high-temperature operating conditions.