Ash deposition behavior during co-combustion of solid recovered fuel with different coals

One of the alternative renewable energy resources that can replace fossil fuels is solid recovered fuel (SRF), derived from municipal waste. However, since SRF possesses high ash and chlorine contents, which are believed to accelerate ash deposition during combustion, thorough investigations on ash deposition are required before large-scale implementation to mitigate the risk of slagging, fouling, and corrosion. In this regard, a comprehensive evaluation is conducted using a blend of SRF (15 wt%) with Si, Al, Mg, Na, and S-rich coal under various parameters such as ash fusion temperature, ash deposits, emissions, ash morphology, and mineralogy. This study comprehensively examines and assesses the effects of SRF blending with different coals on slagging, fouling, and corrosion tendencies. The results indicate that the addition of 15 wt% SRF to various coals poses a high risk of slagging, fouling, and corrosion. Combining SRF with coal causes a decrease in the ash fusion temperature (AFT) value, leading to a higher potential for slagging. Mineral composition aligns with particle structure: coal mainly comprises quartz, anhydrite, and Fe-minerals, while SRF is rich in the low-melting mineral albite. Introducing SRF to coal alters quartz into a mineral with a reduced melting point. In addition, blending with Si- and S-rich coals tends to give comparatively better results on the corrosion side, while visual probe observations show that blending SRF with Mg-rich coal is relatively cleaner than other blends. Therefore, conducting a comprehensive evaluation of co-firing characteristics at a pilot scale, particularly concerning ash-related issues, becomes indispensable for successfully co-firing these fuels in power plants.