Simulation of a biomass treatment process for the production of biofuels with pressurized torrefaction and plasma gasification on Aspen Plus

Biomass is one of the most widely utilized renewable energy sources and is therefore an essential element of sustainable energy production. Different technologies for the direct and indirect utilization of biomass exist. However, biomass is still not fully exploited at its maximum potential, thus further research and development of biomass conversion are necessary. This work aims to offer its contribution to the development of two technologies of focus: torrefaction and gasification. Specifically, the study strives to investigate alternatives to conventional biomass thermo-chemical conversion technologies, namely atmospheric torrefaction and autothermal gasification. A base case thermochemical biomass-to-liquid process, composed of 6 hierarchies is modeled in Aspen Plus for the following sub-systems: torrefaction process, gasification process, quenching, water-gas-shift, acid gas removal, Fischer-Tropsch synthesis and upgrading. The base case model is then subsequently modified with gas-pressurized torrefaction using experimental data to represent the respective process. Another variation is made to the model by converting the conventional gasification process to one that is plasma-fired. The results and effect of the two adjustments are then discussed and compared, taking into consideration the energy yields, carbon conversion and efficiencies. A techno-economic analysis of the gas-pressurized process is also performed.