Process design and simulation of producing liquid transportation fuels from biomass

Abstract

Although the global energy sector is driven by fossil fuels, renewable and more environmental friendly energy sources need to be explored due to the insecurity of crude oil availability in the future and the environmental problems associated with fossil fuel consumption. The conversion of biomass to liquid transportation fuels is one such environmentally friendly process. This is the case since biomass acts as a renewable carbon-based source, having absorbed atmospheric CO2 via photosynthesis. There is also an abundance of biomass on earth. In this work, a process has been designed and analyzed in Aspen Plus. The conversion of biomass to gasoline, diesel, and kerosene at varying design/operating conditions has been simulated. In this process, biomass is dried and gasified to generate synthesis gas, which is converted to a mixture of hydrocarbons via Fischer-Tropsch synthesis (FTS). Given the same biomass feedstock, three FTS technologies including conventional FTS, once-through FTS, and supercritical FTS have been comparatively studied. Hydrocarbons after FTS undergo upgradation to liquid transportation fuels through several technologies (hydrocracking, hydrotreating, isomerization, catalytic reforming, and alkylation) meeting all necessary physical property standards. This study first investigates the product distribution of biomass conversion process associated with the three FTS technologies. Then heat integration is performed to optimize the heat exchanger network. Lastly, a detailed economic analysis is performed using Aspen Process Economic Analyzer and unit cost functions obtained from literature.