Torrefaction of palm kernel shell using COMB method and its physicochemical properties

Abstract

Torrefaction is a pre-treatment in thermochemical processes in order to make biomass becomes fuel with better properties, such as the increasing of carbon content and caloric value. Torrefaction is generally carried out at a temperature range of 200-300°C with holding temperature of 30-60 minutes in inert conditions and atmospheric pressure. On the other side, palm oil is one of biomass that is potential to be used as fuel in which its availability is abundant and has good physical properties. The purpose of this study is to increase the caloric value and thermochemical properties by torefaction process. Within this study of palm kernel shell, torrefaction is carried out from 0.5 cm sieve using the COMB (Counter Flow Multi-Buffle) method at temperature of 250°C with heat flow rate of 4 cm3/minute and characterized by its physicochemical properties. The obtained results are the energy yield of 0.77 with an energy density of 1.21 and the caloric value that increases from 16.82 to 19.11 MJ. This is also supported by the results of ultimate analysis where the carbon level increases then the O/C and H/C ratio decreases. Moreover, based on proximate analysis, volatiles matter level decreases by 9.34% and ash content increases by 0.64%. To sum up, palm kernel shells can be enhanced by their physicochemical characteristics through torrefaction.