Synergistic evaluation of co-torrefaction performance of rice husk and coffee bean ground blends for biosolid production for industrial fuel sustainability

Abstract

Renewable fuel feedstock for industry is in demand to reduce the carbon footprint of industry. This study presents the impact of temperature on co-torrefaction of coffee bean ground (CBG), rice husk (RH) for char production. The co-torrefaction of CBG and RH in different blending ratios such as CBG:RH (25:75%), CBG:RH (50:50%), and CBG:RH (75:25%) was performed using a laboratory scale tube furnace in the temperature range of 200 ℃ to 300 ℃. The C content decreased from 69.25% to 65.24% with the increase of CBG from 0 to 75%. The mass and energy yields decreased with increasing temperature. Along with that, the oxygen-to-carbon ratio decreases by 34.45% containing volatiles with an increase in temperature at the blending ratio of (75:25%). The synergistic behavior of the co-torrefied biosolid accounted for its improved energy density, reduced volatile matter, and increased fixed carbon content. The FTIR spectrum confirmed the release of the functional group of the volatile components such as H2O, CO, and CO2, etc. Furthermore, the synergistic effect and the torrefaction index on a yield basis (weight loss, performance index, and EMCI) predict the better fuel properties that match the biomass CBG:RH (75:25%) at 275 ℃ for 60 min of biosolid production due to the high synergistic effect of value 2.89%. The findings of this study suggest that co-torrefaction is an excellent pretreatment procedure for enhancing the characteristics of CBG, heptane (RH), and their blends used as a biosolid fuel for further sustainable energy applications in industry.