Thermogravimetric analysis of the torrefied Austrian pine

Abstract

ABSTRACT This work investigated the impact of thermal pre-treatment on the thermal kinetics of pinecones. An improvised muffle furnace was used for the torrefaction process. The kinetic parameters for thermal decomposition of torrefied pinecones and the raw pinecones were determined from the isoconversional methods (Friedman, Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS)). The reaction mechanism (RM) of the raw and thermally processed pinecones was obtained by the Criado master plots. Thermogravimetric analyses of both the raw and thermally pre-treated pinecones were performed at a heating rate of 5°C·min−1, 10°C·min−1 and 15°C·min−1. Nitrogen gas was used as an inert medium for both thermal pre-treatment and pyrolysis of raw pinecones. The activation energies estimated from OFW and KAS, and Friedman for torrefied pinecones are 165.87 kJ·mol−1, 169.66 kJ·mol−1 and 130.68 kJ·mol−1,respectively. The calculated value of activation energy from OFW and KAS for the torrefied pinecones was estimated to be 8.66–8.93% higher than that of raw pinecones; however, in the case of the differential method, it decreased by a margin of 10%. The reduced reaction rate of the torrefied pinecones was slightly higher than that of the raw pinecones. However, no change in the characteristics of the reduced reaction rate of torrefied pinecones was noticed with respect to its raw form, in relation to thermal conversion. The clean gas generation after processing the raw pinecones was noticed to be 27.54% higher than its raw form. The weight percentages of alkali elements were increased by 24% after the torrefaction process.