An experimental study to investigate the effect of torrefaction temperature on the kinetics of gas generation

Abstract

Pre-treatment of biomass using torrefaction has been demonstrated to be an efficient process to improve the physical and chemical properties of biomass that can be used as a promising feedstock for gasification and boilers. Karanja, neem, kusum, mahua, and microalgae were the five biomass feedstocks investigated in this work for the torrefaction pre-treatment. The experimental study of torrefaction was carried out in a vertical fixed bed reactor set-up at 200, 250, and 300°C under nitrogen atmosphere. A thorough analysis of gas, liquid and solid products was made and the changes in H/C and O/C ratios in the pre-treated biomass were analyzed by elemental analysis. Among the five biomass feedstocks studied, mahua was found to have the highest heating value of 27.73MJ/kg at 300°C compared to others (neem=19MJ/kg, Karanja=23.3MJ/kg, kusum=25.8MJ/kg, microalgae=26.7MJ/kg). Following a detailed kinetic analysis using the yield of product gas mixtures, it is concluded that the biogases are generated by parallel independent first-order reactions. Also, the activation energy values for the torrefaction reactions of five biomass feedstocks were found to be different from each other