The influence of the elemental and structural chemical composition on the ash fusibility of sugarcane bagasse and sugarcane straw
The influence of the elemental and structural chemical composition on the ash fusibility of sugarcane bagasse and sugarcane straw, K.R.D. Palma, E. Tomaz, A. Soria-Verdugo, M.A. Silva, Fuel, 304, 121404, 2021, Online version, https://doi.org/10.1016/j.fuel.2021.121404
Abstract
Agricultural residues have been pointed out as an important source to energy conversion by direct burning. Nevertheless, their use still faces operational problems, such as slagging and fouling, mainly related to the inorganic fraction of their composition. The objectives of this work were to understand the fusion behavior of sugarcane biomass ash formed during thermal conversion and the tendency of slag and fouling to occur, in addition to propose possible solutions to minimize these problems using a mixture of biomass species and/or additive minerals. To that end, experimental measurements and thermodynamic simulations were employed to relate the chemical composition to the fusibility. The ashes chemical composition was characterized by EDS and XRD, while the ash fusion temperatures AFT́s (DT, ST, HT and FT) were measured by AF700 equipment and estimated using FactSage modeling. Statistical analysis helped to derive the relationship between chemical composition and AFT́s. The ashes were rich in SiO2, Al2O3 and Fe2O3 and revealed that for bagasse the element that most contributes to increase DT is Si, whereas for straw the presence of Al has a stronger effect to increase DT. Fe was found to act as flux element. XRD results showed the phases differences, finding more amorphous components in straw ash than in bagasse, which may lead to a different ash fusion behavior. Straw 2015 ash presented a DT of 733 °C while for bagasse 2015 and 2016 ashes the values of DT were 777 and 917 °C, respectively. In contrast, the DT of straw ash increased when mixed with bagasse 2015 and 2016 to values of 841 and 885 °C, respectively, and also when 1% of Al2O3 was added, obtaining a DT of 930 °C. For bagasse samples, the additives showed a minor effect on ash melting behavior.