Evaluation of Silica-based Additives for Slagging Mitigation in Biomass Combustion: A Thermochemical Approach

https://doi.org/10.22146/jmdt.121139

Abdul Wahid Erlangga(1*), Mochamad Zainudin Ade Arta(2), Muhammad Syarif Hidayatullah(3)

(1) UBP Suralaya, PLN Indonesia Power, Cilegon, Indonesia
(2) UBP Suralaya, PLN Indonesia Power, Cilegon, Indonesia
(3) UBP Suralaya, PLN Indonesia Power, Cilegon, Indonesia
(*) Corresponding Author

Abstract


Slagging and fouling remain key barriers to reliable biomass cofiring in coal-fired boilers due to alkali-rich ashes that form low-melting deposits. This study evaluates a low-cost mitigation route using a 3 wt% natural soil additive (SiO₂–Al₂O₃ rich) and quantifies its impact on alkali release and slag formation for rice husk (RH), sawdust (SD), and empty fruit bunch (EFB). Thermodynamic-equilibrium calculations were performed in FactSage (FToxid + FactPS; Equilib module) over 500–1800 °C, using literature-based ultimate/oxide analyses normalized to 1,000 g fuel and combustion air with 15% excess. Volatile species (K, Na, KCl, NaCl, KOH, NaOH) and slag-phase oxides (K₂O, Na₂O) were tracked; ash-melting behavior was additionally probed under oxidizing and reducing atmospheres. The additive substantially suppressed alkali volatility for moderate-alkali biomasses. In RH, KCl(g) and KOH(g) declined by ~40–45%, with ~50% reduction in total gaseous alkalis. In SD, KOH(g) and K(g) fell by 52% and 46%, and slag-phase K₂O decreased by 51%, indicating stabilization via aluminosilicate formation. For EFB, the inherently high K limited mitigation: KOH(g) decreased ~25%, while K₂O(s) increased ~80%, evidencing partial capture but persistent high volatility. Overall, natural soil is a practical, locally available additive that can lower alkali volatilization by up to ~50% for RH and SD, thereby reducing slagging/corrosion risk in cofiring. High-K EFB will likely require higher dosages, fuel blending, or pre-treatments. The results provide quantitative guidance for additive selection and dosing to enhance operational reliability in biomass cofiring.


Keywords


Slagging; biomass; additive; silica; soil; cofiring; FactSage; thermodynamic modeling.

Full Text:

PDF


References

Blomberg T. (2011). A thermodynamic study of the gaseous potassium chemistry in the convection sections of biomass fired boilers. Mater Corros, 62, 635–41. http://dx.doi.org/10.1002/maco.201005880

De Geyter S, Ohman M, Bostrom D, Eriksson M, Nordin A. (2007). Effects of non-quartz minerals in natural bed sand on agglomeration characteristics during fluidized bed combustion of biomass fuels. Energy Fuels, 21:2663–8. http://dx.doi.org/10.1021/ef070162h

Elled AL, Davidsson KO, Amand LE. (2010). Sewage sludge as a deposit inhibitor when co-fired with high potassium fuels. Biomass Bioenergy, 34(11), 1546–54. http://dx.doi.org/10.1016/j.biombioe.2010.05.003

Li L, Yu C, Huang F, Bai J, Fang M, Luo Z. (2012). Study on the deposits derived from a biomass circulating fluidized-bed boiler. Energy Fuels, 26(9), 6008–14. http://dx.doi.org/10.1021/ef301008n.

Liaw SB, Wu H. (2013). Leaching characteristics of organic and inorganic matter from biomass by water: differences between batch and semi-continuous operations. Ind Eng Chem Res, 52, 4280–9. http://dx.doi.org/10.1021/ie3031168

Mohammed, M. A. A., Salmiaton, A., Wan Azlina, W. A. K. G., Mohamad Amran, M. S. (2012). Gasification of oil palm empty fruit bunches: A characterization and kinetic study. Bioresource Technology, 110, 628–636. https://doi.org/10.1016/j.biortech.2012.01.056

Niu YQ, Tan HZ, Ma L, Pourkashanian M, Liu ZN, Liu Y, et al. (2010). Slagging characteristics on the superheaters of a 12 MW biomass-fired boiler. Energy Fuels, 24, 5222–7. http://dx.doi.org/10.1021/ef1008055

Niu, Y., Wang,, Z. Zhu, Y., Zhang X., Tan, H, Hui, S. (2016). Experimental evaluation of additives and K2O–SiO2–Al2O3 diagrams on high-temperature silicate melt-induced slagging during biomass combustion. Fuel, 179, 52-59. https://doi.org/10.1016/j.fuel.2016.03.077

Nutalapati D, Gupta R, Moghtaderi B, Wall TF. (2007). Assessing slagging and fouling during biomass combustion: a thermodynamic approach allowing for alkali/ash reactions. Fuel Process Technol, 88, 1044–52. http://dx.doi.org/10.1016/j.fuproc.2007.06.022

Reichelt J, Pfrang-Stotz G, Bergfeldt B, Seifert H, Knapp P. (2013). Formation of deposits on the surfaces of superheaters and economisers of MSW incinerator plants. Waste Manage, 33(1), 43–51. http://dx.doi.org/10.1016/j.wasman.2012.08.011

Rizvi, T., Xing, P., Pourkashanian, M., Darvell, L. I., Jones, J. M., Nimmo, W. (2015). Prediction of biomass ash fusion behaviour by the use of detailed characterisation methods coupled with thermodynamic analysis. Fuel, 141, 275–284. https://doi.org/10.1016/j.fuel.2014.10.021J

Wei XL, Schnell U, Hein KRG. (2005). Behaviour of gaseous chlorine and alkali metals during biomass thermal utilisation. Fuel, 84, 841–8. http://dx.doi.org/10.1016/j.fuel.2004.11.022

Xing, P., Darvell, L. I., Jones, J. M., Ma, L., Pourkashanian, M., Szuhánszki, J., (2019). The use of equilibrium thermodynamic models for the prediction of inorganic phase changes in the co-firing of wheat straw with El Cerrejon coal. Journal of the Energy Institute. 92(3), 813–823. https://doi.org/10.1016/j.joei.2018.02.003

Yang TH, Kai XP, Sun Y, He YG, Li RD. (2011). The effect of coal sulfur on the behavior of alkali metals during co-firing biomass and coal. Fuel, 90, 2454–60. http://dx.doi.org/10.1016/j.fuel.2011.02.031



DOI: https://doi.org/10.22146/jmdt.121139

Article Metrics

Abstract views : 6 | views : 1

Refbacks

  • There are currently no refbacks.


Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.