Investigation on Ash Melting Characteristics and Additive Co-firing of Coal and Biomass

Converting coal-fired power plants into combined coal and biomass power generation systems not only optimizes the use of biomass resources but also significantly curtails CO2 emissions during electricity production, aiding in the pursuit of carbon peak and neutrality goals. Nonetheless, integrating biomass fuel into these systems can modify the original fuel’s ash fusion behavior. This research primarily examines the co-combustion of Ordos bituminous coal (BC) and corn stover (CS) and investigates the ash fusion properties post-co-combustion through the use of additives. Techniques employed for analysis include an ash fusion point tester, X-ray fluorescence (XRF), and X-ray diffraction (XRD), coupled with mineral transformation simulations via Factsage software. The findings reveal that CS’s ash fusibility temperature (AFT) is notably lower compared to BC, and the AFT tends to decline with an increasing blend ratio. The strategic addition of certain additives significantly elevates the AFT of the mixed fuel. The presence of CS encourages the formation of silicates with lower melting points, whereas additives like MgO, Kaolin, and Ca(H2PO4)2 promote the creation of minerals with higher melting points, thus enhancing the AFT of the blended fuel. Observations show varying efficacy of these three additives in the co-firing system with different CS proportions. These experimental insights offer practical guidance for power plants in terms of biomass co-firing and selecting appropriate additives.