Novel Thermal and Microscopic Techniques To Determine the Causes of Suboptimal Combustion Performance at Colombian Stoker Furnaces

Williams, Orla Sioned Aine; Daley, Patrick; Perkins, Joseph; Shah, Shoaib; Saavedra, Edward Andres Garcia; Trujillo, Maria; Barraza-Burgos, Juan; Espitia, Carlos Julio; Barajas, Maribel; Saltaren, Juan Sebastian; Gil, Nicolás Javier; Lester, Edward Henry

Abstract

This study presents the application of a novel approach, using thermal and optical techniques, to identify the causes of poor burnout performance of Colombian stoker furnaces in the Cauca Valley State. The four coals used in these furnaces were characterised to obtain particle size distribution, particle and tapped density, elemental and proximate composition, mineral composition, and maceral content. Up to 80% incomplete combustion was noted in macro-TGA tests compared to complete combustion in a micro-TGA. Reflectance and intrinsic reactivity measurements were for chars prepared in 3 different particles sizes (<6, 6-19, 19 mm), 3 temperatures (700, 900, 1050 °C) and 3 residence times (10, 30, 120 minutes). Two of the coals produced char samples with reflectance values above 6%, which matched those seen in the stoker, indicating furnace temperature was not the cause of poor combustion and that only two of the four coals were likely to be present in the furnace bottom ash. These tests were also able to prove that oxygen diffusion limitation was the root cause of the poor burnout where the carbon inside the furnace bottom ash was shielded from oxygen ingress through the formation of a non-permeable slag layer. Thus, this study demonstrates the potential of both thermal profiling and optical reflectance as a tool for forensically evaluating the thermal history and operational performance of furnaces.

Citation

Williams, O. S. A., Daley, P., Perkins, J., Shah, S., Saavedra, E. A. G., Trujillo, M., …Lester, E. H. (2022). Novel Thermal and Microscopic Techniques To Determine the Causes of Suboptimal Combustion Performance at Colombian Stoker Furnaces. ACS Omega, 7(14), 11618–11630. https://doi.org/10.1021/acsomega.1c06314

• Journal Article Type: Article
• Acceptance Date: Feb 2, 2022
• Online Publication Date: Apr 1, 2022
• Publication Date: Apr 12, 2022
• Deposit Date: Feb 14, 2022
• Publicly Available Date: Apr 2, 2022
• Journal: ACS Omega
• Electronic ISSN: 2470-1343
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 7
• Issue: 14
• Pages: 11618–11630
• DOI: https://doi.org/10.1021/acsomega.1c06314
• Keywords: General Chemical Engineering; General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/7466433
• Publisher URL: https://pubs.acs.org/doi/10.1021/acsomega.1c06314