Simulation and modelling of torrefaction and activation of oil palm trunk to produce activated charcoal

Abstract

This paper concerns on process modeling of torrefaction and activation of oil palm trunk (OPT) becoming activated charcoal, abundant biomass resources coming from replantation of oil palm. The processes are very crucial in treating OPT before utilization for energy source due to the high level of water content and volatile matters in the biomass. Oil palm trunk is solid waste biomass from oil palm, which can be a new and renewable energy source with great potential in Indonesia. One way to increase the value of oil palm trunk is by increasing its calorific value. Utilization of this OPT waste will be used to produce fuel that is relatively more environmentally friendly. One of the processes to increase the calorific value of the OPT is torrefaction, and its use-value can be increased again by the activation process to produce activated carbon. In this research, modeling and simulation were carried out on the drying process and OPT torrefaction using three types of reactors of the Gibbs reactor, Yield reactor, and Batch reactor. Oil palm trunk is defined as cellulose, hemicellulose, extractive, ash, and water. The simulation results in the form of HHV and yield values were then validated with experimental data. Statistical analysis to determine the effect of HHV charcoal and impregnation ratio (IR) on the surface area was carried out by collecting and processing literature data. For the torrefaction process, the difference between the simulation results and the experiment on the Gibbs reactor is about 5 % for HHV and about 10 to 14.94% for yield. Meanwhile, the yield reactor has an error about 12 to 19% for HHV and 5 % for yield. Based on the sensitivity analysis, the optimum temperature for the torrefaction process is 275°C. Based on statistical analysis, the impregnation ration of ZnCl2 to produce the maximum surface area of 1652.507 m2/g is 5.458.