Experiment and Simulation of Rice husk Gasification Process with a Downdraft Gasifier

Abstract

In this study, the gasification of rice husk in a downdraft process is simulated by Aspen Plus software to predict an appropriate operation condition for designing small-scale equipment. Gibbs models of the reactions occurring in the process are applied for the simulation while tuning the equivalence ratio (ER) to forecast the syngas’ compositions. Based on the analysis, ER value of 0.096 is selected to generate a syngas mixture consisting of CO (43.26 mol%), CH4 (0.09 mol%), and H2 (33.87 mol%), corresponding to the optimal calorific value of 8.92 MJ/kg and efficiency of 86.98 %. A real experiment is performed with the small-scale gasifier to evaluate the results obtained from the simulation. The pilot results show that not only the input air flow rate but other confounding factors also affect the combustion efficiency at some degree, which is compatible with the simulation model. The total energy value acquired from the conversion of 5.0 kg of dry rice husk was 86.82 MJ, while the energy value of the syngas obtained was 44.42 MJ syngas.