Structure-governed potassium retention mechanism in the slagging and non-slagging gasification condition of corn straw

Mengran Yuan, Jing Guo, Chong He, Alexander Ilyushechkin, Xiaoming Li, Hao Lu, Feifei Fan, Zhigang Wang, Yuhong Qin, Yuexing Wei, Jin Bai and Wen Li

Renewable Energy, 2025, vol. 239, issue C

Abstract: Understanding the potassium retention mechanism in biomass gasification is the key for mitigating the severe ash-related issues (deposition, low slag viscosity, etc.) to gasifier operation. In this study, the kaolin addition was effective in K retention in both non-slagging and slagging gasification conditions, albeit through distinct mechanisms. In the non-slagging condition, K retention in the dry ash was predominantly governed by the crystallization kinetics of minerals with various K retention abilities. Notably, leucite demonstrated the highest retention ability followed by kalsilite and KAlO2. In contrast, the K retention was mainly thermodynamically controlled in the slagging gasification condition. The charge-compensation effect of K+ to the four-coordinated Al3+ was key for the K retention, and the Si-O-Al bond was converted to Si-O-KAl with kaolin addition. Moreover, a novel method for determining the Gibbs free energy (ΔG) of slag in the K capture reaction was introduced, demonstrating a decrease in ΔG from −16.66 kJ/(mol⋅K−1) to −57.67 kJ/(mol⋅K−1) with a 5 wt% kaolin addition, resulting in a 38.46 % increase in K retention. Finally, the viscosity of the biomass slag was empirically correlated with the K release ratio (R2 = 0.95), providing one stone for two birds strategy for addressing ash deposition and slag mobility issues.

Keywords: Biomass gasification; Potassium retention mechanism; Kaolin addition; Bond distribution; Slag viscosity (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:239:y:2025:i:c:s0960148124022493

DOI: 10.1016/j.renene.2024.122181

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