Inferences from thermogravimetric analysis of pine needles and its chars from a pilot-scale screw reactor

Abstract

Pine needles are the waste of pine forest and produced in a substantial amount every year during the fall. If not extracted from forest bed, they cause a widespread forest fire. In this study, pine needles were converted to char at different temperatures using a screw type pyrolyzer with an aim to find out the effect of thermal stress on the properties of chars and their intended end uses. The chars were evaluated for intrinsic physico-chemical transformations in comparison with the raw pine needles. Differences between chars produced in three temperatures and the raw biomass were studied by thermogravimetric analysis. It was found that the char produced at higher temperature showed a superior profile of apparent activation energy as compared with the char from low temperature. Coats–Redfern kinetics was used to compare the activation energies of chars and raw biomass, which showed that the char obtained from higher temperature had better thermal stability. From this study it can be concluded that chars produced at low temperatures in the screw reactor are useful as source of fuel, whereas the char of higher temperature is suitable for soil application and preparation of activated char.