Combustion and Kinetics Parameters Investigation of Raw and Torrefied Cocoa Pod Shells by Thermogravimetric Analysis

Abstract

Torrefaction is one of the techniques to produce solid fuel from cocoa pod shell (CPS). In this research, changing combustion characteristic and kinetics of CPS after torrefaction process was investigated using Coats – Redfern Method. Torrefied CPS processed at temperatures of 200, 250, and 300°C and holding times of 0, 30, 60, and 90 min were used in this investigation. The results proved that the ignition and burnout temperatures shifted to higher value, while the peak mass loss rate tend to lower value when the torrefaction temperature and the holding time increased. The period of volatile release during the combustion process was shorter along with longer holding time and higher temperature of torrefaction. The maximum mass loss rate of raw CPS was 0.12005 g/min, while torrefied CPS has range between 0.046 to 0.114 g/min. The maximum mass loss rates of all samples decrease with increasing fuel ratio (FR). The activation energy increases gradually with increasing severity of torrefaction. The value of activation energy in the devolatilization and volatile combustion stage is greater compared to that of the char combustion stage.