Sugarcane vinasse CO₂ gasification and release of ash-forming matters in CO₂ and N₂ atmospheres

Gasification of sugarcane vinasse in CO₂ and the release of ash-forming matters in CO₂ and N₂ atmospheres were investigated using a differential scanning calorimetry and thermogravimetric analyzer (DSC-TGA) at temperatures between 600 and 800 C. The results showed that pyrolysis is the main mechanism for the release of the organics from vinasse. Release of ash-forming matters in the vinasse is the main cause for vinasse char weight losses in the TGA above 700 C. The losses are higher in N₂ than in CO₂, and increase considerably with temperature. CO₂ gasification also consumes the carbon in the vinasse chars while suppressing alkali release. Alkali release was also significant due to volatilization of KCl and reduction of alkali sulfate and carbonate by carbon. The DSC measured thermal events during heating up in N₂ atmosphere that correspond to predicted melting temperatures of alkali salts in the char.