Combustion of the banana Pseudo-stem hydrochar by the High-Pressure CO2-Hydrothermolysis: Thermal conversion, kinetic, and emission analyses

Abstract

Due to slow degradation and potentially carrying fungus of banana pseudo-stem, the irresponsibly disposed (such as optionally dumping and burning on the spot) of banana pseudo-stem caused severe environmental problems and fungus disease. However, the combustion efficiency of the banana pseudo-stem was limited by the higher moisture and lower heating value. The high-pressure CO2-hydrothermolysis provides an efficient strategy for upgrading the fuel quality and combustion characteristics. In this study, the combustion characteristics and emission analyses of the sample after and before treatment were investigated by TG–FTIR. Meanwhile, the oxidation reaction kinetics of the sample was established using the Friedman method. The results showed that the “coal-like” fuel, higher heating value (HHV) between 13.64 and 25.76 MJ/kg, was produced from banana pseudo-stem by the high-pressure CO2-hydrothermolysis. The ignition temperature of the sample after treatment is higher than that of the banana pseudo-stem. However, the combustion character index of the sample after treatment at 160 °C (BP-160) is the best among all samples, but that of the sample after treatment at 280 °C (BP-280) is the lowest. The sample after treatment has the higher combustion reactivity except for BP-280. The averaged activation energy values of the sample after treatment decrease with the increased temperature and are higher than that of BP, except for BP-280. The carbon emission (CO2 + CO), SO2 and N species emission (NO + N2O) was reduced during sample combustion after treatment. Overall, the high-pressure CO2-hydrothermolysis is a promising treatment technology for minimizing and energy utilization of banana waste.