Development of the Process Model and Optimal Drying Conditions of Biomass Power Plants

An empty fruit bunch (EFB) is a byproduct of the palm oil production process with an undried moisture content of 60-70%, which is too high for use as direct combustion fuel. Drying processes are generally considered essential for the recent use of EFBs as power plant fuels because their high moisture content decreases the boiler efficiency. The lower moisture content of dried EFBs increases the heating value and boiler efficiency but creates a trade-off with the energy required for the drying process. This study developed an EFB-based 10 MW power plant model by integrating economic evaluations in order to obtain optimal drying conditions. A hot air dryer was used in the drying process. The EFB evaporation behavior was predicted by reflecting the drying kinetics of EFBs in Aspen Plus. The optimum drying conditions were found to be a steam recirculation ratio of 0.25 and drying time of 23 min, creating dried EFBs with a 9.91% moisture content, which reduced costs by 5.48% relative to the undried base scenario. In addition, the developed model was compared to the drying process of a real power plant currently under construction in Indonesia. This drying process reduces the EFB moisture content from 48 to 20%.