Effect of acid leaching on the ash fusion behavior and slagging/fouling indices of bagasse: focus on potassium and chlorine removal

초록

Managing ash-related issues, such as slagging, fouling, and corrosion, is critical for the energy utilization of agricultural residues. This study proposes a sustainable pretreatment using mild organic acids to enhance the combustion characteristics of bagasse, specifically focusing on the selective removal of potassium (K) and chlorine (Cl). Under optimal conditions (80 °C for 30 min), the process achieved maximum removal efficiencies of 96.8% for K (with citric acid) and 93.4% for Cl (with oxalic acid), while maintaining high solid recovery. X-ray diffraction analysis revealed that while the mineral framework remained stable, the treatment effectively targeted problematic low-melting-point species. This improvement significantly enhanced the ash fusion behavior, with the initial deformation temperature (IDT) increasing from 1130 °C to beyond the instrument’s maximum measurable temperature of 1500 °C. Furthermore, comprehensive evaluations using predictive indices (base-to-acid ratio, bed agglomeration index, fouling index, and slag viscosity index) indicated a consistent transition from high-risk to low-risk regimes. Citric acid was identified as the most effective solvent due to its superior selectivity and energy preservation. These results demonstrate that organic acid leaching is a practical strategy for upgrading low-quality biomass into high-grade biofuels, ensuring the operational reliability of biomass-fired power systems.

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