Fuel Characterization and Process Analysis of Hydrothermal Liquefaction of Algae

Abstract

The conversion of microalgae to biocrude by hydrothermal liquefaction (HTL) is a technology that could reduce the use of fossil fuels. The aim of this study was to provide insight in the fuel characterization and process analysis of algae HTL. Three microalgae species were provided for the fuel characterization. The Phaeodactylum tricornutum algae were received as a slurry, while the Spirulina platensis and Chlorella vulgaris were received as dried powders. Experiments by TGA, proximate and ultimate analysis were performed on the three algae species. A process analysis of algae HTL was carried out in Aspen Plus. Properties from the algae analysis was used in the simulation model. Great improvement of the process effciency was obtained by implementing a heat exchanger in the simulation model. The S: platensis and P: tricornutum algae obtained 83 % energy effciency in the process analysis, when all the products from the process were utilized. Water recycling or district heating could further improve the energy effciency of the system. For fuel characterization, the C: vulgaris algae had the best properties. In the process analysis, the P: tricornutum algae obtained the best results. In future work a kinetic simulation should be designed in order perform yield optimization and increase the accuracy of the system.