Abstract
In this work, effects of process parameters on hydrothermal gasification (HTG) of biogas digestate are investigated using Aspen Plus software with an assumption that the inorganic contents of feedstock are lumped together as a single input parameter. The investigated parameters are temperature (400-600 oC), pressure (250-300 bar), feedstock concentration (10-50 wt%), and feedstock ash content (0-40%), while the performance indicators are producer gas yield and composition. According to the modelling results, significant effects on the producer gas yield and composition were observed for temperature and feed concentration changes. On the other hand, pressure only had slight effects on the gas production. Hydrogen composition can be enhanced by keeping the pressure and feedstock composition low while increasing the reaction temperature. Furthermore, higher ash content leads to higher H2 composition, lower CO2 and CH4 composition, and higher gas yield. However, the trends captured in this study does not represent any chemical activities of the ash components.
