Andrés Felipe Ospina, William Alexander Ojeda, Thomás Pantoja and Nicolás Javier Gil
Cenicaña, Cali, Colombia; afospina@cenicana.org
The Colombian sugarcane agro-industry produces approximately 5.3 Mt of sugarcane harvest residues (SCHR) annually, which could replace between 0.41 and0.54 t of coal per tonne of SCHR used, achieving a 96% reduction in GHG emissions. However, SCHR presents technical challenges due to its high potassium, chlorine, and sulphur content, which promotes fouling and corrosion on heat exchange surfaces. The impact of using SCHR as fuel on boiler thermal efficiency, fouling formation, and dioxin and furan (PCDD/PCDF) emissions was evaluated at an industrial scale. Four tests were conducted using bagasse and coal mixtures (2.6% and 4.0% SCHR) in two industrial boilers. Biomass and coal samples were characterized with X-ray fluorescence spectroscopy (XRF) using ASTM methods Fouling deposits were collected using a fouling probe exposed to combustion gases for 10 to 22 days of continuous operation in each boiler and were then characterized. Fouling and corrosion risk indicators were correlated with the fuel characteristics. Thermal efficiency decreased as the proportion of SCHR in the mixtures increased, with an efficiency of 59.1% using only bagasse to 54.3% when bagasse was blended with 4% of SCHR. The main reasons for this reduction were the higher moisture of SCHR, the increment of unburned material, and the heat losses in the flue gas. Although PCDD/PCDF emissions increased with the use of SCHR, they remained significantly below the regulatory limit of 500 pg/m³, with the maximum measured value being 30 pg/m³. This study offered valuable insights into fouling challenges in industrial boilers using SCHR, identifying conditions affecting combustion efficiency. A testing methodology, including analysis methods and a fouling probe, was established to optimize future projects with other biofuels and to support energy transition.