A Pilot–Scale Continuous Torrefier for Bagasse Quality Improvement in a Biomass Powerplant

Torrefaction is a process that occurs in airless spaces between 200 and 300 ℃. Its purpose is to improve the characteristics of fuels with a higher heating value. In this work, raw bagasse was torrefied in a sugar mill for 12, 15, and 17 min at temperatures between 200 and 210 ℃. Utilising waste heat from exhaust steam as a heat source reduces the operating cost of the process. This enables the pilot program feasible. Parameters including ultimate analysis (CHONS), high heating value (HHV), mass yield (MY), energy densification ratio (EDR), and energy yield (EY) were evaluated in order to determine the optimal conditions for bagasse torrefaction in an actual application. The results indicate that at 200 ℃ and 15 min of holding time, the MY of 63.99%, the EDR of 1.58, and the HHV of 12,245 kJ/kg are obtained, resulting in an EY of 101.21%. The atomic H/C and O/C ratios of the torrefied bagasse are 1.46 and 0.87, respectively, according to the CHONS analysis. In actual operation, a mixture of raw bagasse and torrefied bagasse will be used as fuel in a biomass boiler, which is expected to prolong the use of bagasse and increase electricity production. Finally, the pilot-scale continuous torrefier can serve as a model for sugar mills.