Ash Transformation and Agglomeration Risks in Coal–Biomass Cofiring: Insights from Thermodynamic Simulations in Fluidized Bed Furnaces
Keywords:
ash behaviour, biomass cofiring, fouling, slagging, agglomeration, thermodynamic modellingAbstract
Biomass cofiring in circulating fluidized bed (CFB) systems offers a transitional strategy to reduce carbon emissions from coal-fired power generation. However, ash behavior remains a major challenge, particularly regarding slagging, fouling, and bed agglomeration phenomena. This study utilizes thermodynamic equilibrium modeling via FactSage to predict ash transformation pathways in various coal–biomass blends (BB100–BB50) under reducing conditions and silica addition. Results show a clear temperature threshold (~1000 °C) beyond which slag formation significantly accelerates, primarily driven by eutectic interactions between alkali metals (Na, K) and silicate matrices. Meanwhile, fouling potential—quantified by gas-phase NaOH, KOH, and sulfates—peaks at high temperatures but declines with increasing biomass ratio due to its lower volatile alkali content. Solid-phase analysis identifies CaAl₂Si₂O₈ and Mg₂Al₄Si₅O₁₈ as dominant inhibitors stabilizing ash, whereas promoters such as FeS and alkali feldspars diminish as biomass increases. These insights highlight the importance of fuel composition, temperature control, and mineral equilibria in managing ashrelated operational risks in CFB cofiring applications.
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References
United Nations Framework Convention on Climate Change (UNFCCC), The Paris Agreement, https://unfccc.int/process-and-meetings/the-parisagreement, (Accessed: 12 August 2025). (URL Link)
Intergovernmental Panel on Climate Change (IPCC), AR6 Climate Change 2021: The Physical Science Basis, https://www.ipcc.ch/report/ar6/wg1/, (Accessed: 12 August 2025). (URL Link)
International Energy Agency (IEA), World Energy Outlook 2022, https://www.iea.org/reports/world-energy-outlook-2022, (Accessed: 12
May 2025). (URL Link)
Demirbas, A., Sustainable co-firing of biomass with coal, Progress in Energy and Combustion Science, Vol. 29, Issue 6, 2003, pp. 585–630.
PT PLN (Persero), Punya Potensi Besar, PLN Kembangkan Biomassa Berbasis Keterlibatan Masyarakat, https://web.pln.co.id/media/siaranpers/2023/09/punya-potensi-besar-pln-kembangkan-biomassa-berbasisketerlibatan-masyarakat, (Accessed: 14 August 2025). (URL Link)
Vassilev, S. V., Baxter, D., Andersen, L. K., Vassileva, C. G., An overview of the composition and application of biomass ash, Fuel, Vol. 89, Issue 5, May 2010, pp. 913–933. https://doi.org/10.1016/j.fuel.2009.09.024. (Journal)
Baxter, L. L., Biomass-Coal Co-Combustion: Opportunity for Affordable Renewable Energy, IEA Bioenergy Task 32, 2005. (Book)
Jenkins, B. M., Baxter, L. L., Miles Jr., T. R., Miles, T. R., Combustion properties of biomass, Fuel Processing Technology, Vol. 54, Issues 1–3, March 1998, pp. 17–46. https://doi.org/10.1016/S0378-3820(97)00059-3. (Journal)
Vassilev, S. V., Baxter, D., Vassileva, C. G., An overview of the behaviour of biomass during combustion: Part II. Ash fusion and ash formation mechanisms of biomass types, Fuel, Vol. 117, 2014, pp. 152–183. https://doi.org/10.1016/j.fuel.2013.09.024. (Journal)
Aho, M., & Ferrer, E., Importance of coal ash composition in protecting the boiler against chlorine deposition during co-firing of coal and biomass, Fuel, Vol. 87, Issues 3–4, 2008, pp. 243–251. https://doi.org/10.1016/j.fuel.2007.05.021 (journal)
Scala, F., & Chirone, R., An SEM/EDX study of bed agglomerates formed during fluidized bed combustion of three biomass fuels, Biomass and Bioenergy, Vol. 32, Issue 3, March 2008, pp. 252–266. https://doi.org/10.1016/j.biombioe.2007.10.005 (journal)
Anicic, B., Jørgensen, R. B., Glarborg, P., & Dam-Johansen, K. (2018). Agglomeration in fluidized bed combustion of biomass: Mechanisms, modeling and preventive measures. Energy & Fuels, 32(5), 5433–5447.
https://doi.org/10.1021/acs.energyfuels.7b03727
Li, X., Wu, H., & Sander, D. (2013). Agglomeration and defluidization mechanisms of biomass ash in fluidized beds. Energy & Fuels, 27(3), 1359–1367. https://doi.org/10.1021/ef301972g
Niu Y, Tan H, Liu Y, Hui S, Yu C, Liu H, Xu T. Study on slagging characteristics of high-sodium coal during combustion. Fuel. 2016;164:141–8. https://doi.org/10.1016/j.fuel.2015.10.039
Moradian F, Tchoffor PA, Davidsson KO, Pettersson A, Backman R. Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized‑bed gasification of forest residues. Fuel Process Technol. 2016;154:1–11 https://doi.org/10.1016/j.fuproc.2016.08.014
Elled AL, Åmand LE, Steenari BM. Composition of agglomerates in fluidized bed reactors for thermochemical conversion of biomass and waste fuels: experimental data in comparison with predictions by a thermodynamic equilibrium model. Fuel. 2013;111:696–708
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