Pyrolysis, combustion and oxy-combustion studies of sugarcane industry wastes and its blends

The aim of this work was on the thermal characterization of wastes of the sugarcane industry, such as bagasse, filter cake and vinasse, in both forms: pure and blended. Thermogravimetric analysis (TG), derivative thermogravimetric (DTG) and differential thermal analysis (DTA) were used for the evaluation of the thermal behavior of the samples under four different atmospheres: N2, CO2, N2/O2 and CO2/O2. Comparison of thermal behavior of the samples under combustion (N2/O2) and oxy-combustion (CO2/O2) reveals that replacing N2 by CO2 causes displacement of mass loss steps to higher temperatures and increases some DTG peaks. Higher heat capacity of carbon dioxide and higher partial pressure of CO2 molecules in relation to N2 ones explain these observations. Under CO2 (100 %) environment, an endothermic event—due to CO release—is observed at around 900 °C, which is attributed to the reverse Boudouard reaction. Interestingly, in all samples, when vinasse is present, such endothermic event starts at lower temperature (~700 °C), which can be understood as a reaction catalyzed by the high potassium content in the vinasse. Synergistic effect studies indicated that bagasse improved reactivity of blends due to its higher volatile content. Since there are no reports regarding the thermal characterization of wastes of the sugarcane industry under combustion, oxy-combustion and gasification atmospheres, this work establishes an important database for the study of similar types of biomass in the field of bioenergy.