Design and Engineering Assessment of a Microwave-Assisted Pyrolysis Reactor for Biochar Production from Oil Palm Empty Fruit Bunch Pellets

Abstract

The microwave assisted pyrolysis provided a fast volumetric heating for converting lignocellulosic biomass to biochar. However, the implementation at laboratory scale needs coordinated controlling among heating system, handling of inert gas, temperature controller, steam condensation, and gas collection. This research designed and assembled microwave assisted pyrolysis at laboratory scale for making pellets from empty fruit bunch (EFB) and evaluated its engineering configuration and operation condition range. EFB pellets with diameter of 6–8 mm and long of 10–12 mm was processed for 15 min. Microwave used power level of 450, 500, 550, dan 600 W, mass of biomass of 100, 150, 200, and 250 g. This system integrated with a 30 L microwave chamber with maximum power of 1,200 W, inlet and outlet nitrogen duct, thermocouple, glassware for vapor condensation, a 47 L cooling water reservoir, peristaltic pump, gas trap and gas container. Based on regulated power and time process, the input of nominal microwave energy in the range of 0.1125–0.1500 kWh per batch with equivalent to 0.45–1.50 kWh/kg in the range of used feed mass. This assembled configuration provided a compact experimental platform to systematically evaluate the effect of microwave power and biomass amount, thus to physically separate heating, condensation, and permanent gas handling stages. Quantitative optimization of biochar yield and biochar quality still require characterized data of product for the best result of this research.

Keywords: Biochar, Pellets, Microwave-Assisted Pyrolysis, Empty Fruit Bunch, Reactor Design.