Modelling and thermodynamic assessment of biofuel production process from biomass with the SAFT-VR approach

Two reliable methods for fuel production from biomass including supercritical water gasification (SCWG) and hydrothermal upgrading (HTU) have been studied. The Gibbs free energy minimization method was used to calculate equilibrium mole fraction of the reaction products for glucose and cellulose supercritical water gasification and hydrothermal upgrading of wood as feed biomass. The phase behavior and phase equilibrium of the separators used for the target product separation (hydrogen in SCWG and biocrude in HTU processes) was carried out successfully using the SAFT-VR equation of state for the first time. The effect of pressure and temperature on SCWG process was investigated and turned out that temperature increase causes more hydrogen production while the pressure effect was insignificant. Finally, the exergy analysis and efficiency calculations were performed respectively for HTU and SCWG processes. According to the outcomes, the exergy efficiency and SCWG efficiency for glucose were obtained as 83.63% and 88.28%.