Effectiveness of different additives on slagging and fouling tendencies of blended coal

Indonesian coal reserves are dominated by medium and low-rank coals. Despite being economically profitable, low-quality coals can trigger ash-related problems in a boiler, such as slagging and fouling. Suitable additives can be useful to overcome the issue of high-alkali coals. The main objective of this study is to determine the effectiveness of the three additives in reducing slagging and fouling risks using a drop tube furnace. Aluminum silicate-based, aluminum-based, and magnesium-based additives were used in coal combustion to comprehensively evaluate ash fusion temperature, thermal properties, ash deposit, emission, and ash mineral morphology. The results showed that additives in high-risk coal/blended coal could reduce ash sintering during the combustion. It can lower the ash fusion temperature yet reduce slagging ash deposits and flue gas emissions. Si–Al, Al, and Mg minerals play a role in increasing the ash melting point. Among three additives, the aluminum-based additive can increase the R_max value, resulting in more stable conditions during the combustion.