In this study, sugarcane vinasse and a soda black liquor were pyrolyzed. Vinasse is a by-product obtained from the distillation stage of the integrated sugar-ethanol process, whereas black liquor is a by-product from pulp mills. Today, vinasse is mainly used for fertirrigation while black liquor is burned in a chemical recovery boiler to produce energy from the organics and to recover the pulping chemicals as a molten salt out of the bottom of the boiler.
The pyrolysis experiments were carried out using two different temperatures, 400 and 500 °C. The vinasse and black liquor samples used were dried and ground to a fine powder prior to pyrolysis. About 40 g of the prepared sample was fed into an N2-purged reactor in small batches. The total feeding time was about 1 h. The oil and water vapor produced in the reactor were condensed in a series of three condensers, which were cooled to -40 °C. To capture aerosols, two cotton filters were installed after the third condenser. CO, CO2, and the total carbon in the non-condensable gaseous product were analyzed by directing part of the gas to a CO/CO2 analyzer and by mixing part of the gas with air and burning in a quartz glass reactor in an electrically heated oven followed by analysis of CO2. After each experiment, the char and oil yields were determined gravimetrically. The gas yield was calculated from the gas flow and measured concentrations. The water content of the condensed pyrolysis oils was analyzed using Karl Fischer titration. The results showed that the water-free oil yield was in the range of 6-9 on a wt% original dry biomass basis. There was a significant difference in the gas compositions; the main constituent in the gas from vinasse pyrolysis was CO2, whereas with black liquor, the CO to CO2 ratio was close to one. In addition, all the K in the vinasse was recovered in the pyrolysis char indicating that pyrolysis may be an option for the recovery of K from vinasse for fertilizer.
|Publication status||Published - 2017|
- black liquor