RESUMO
Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220375 °C, 20255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid residue, and recycling process water for algae cultivation. GCMS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained on N. salina at 350 °C and 175 bar. For S. platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for N. salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins.
Assuntos
Fracionamento Celular/métodos , Cianobactérias/química , Lipídeos/isolamento & purificação , Água/química , Estudos de Viabilidade , Temperatura Alta , PressãoRESUMO
Initial process studies carried out in Aspen Plus on an integrated thermochemical conversion process are presented herein. In the simulations, a hydrothermal liquefaction (HTL) plant is combined with a biogas plant (BP), such that the digestate from the BP is converted to a biocrude in the HTL process. This biorefinery concept offers a sophisticated and sustainable way of converting organic residuals into a range of high-value biofuel streams in addition to combined heat and power (CHP) production. The primary goal of this study is to provide an initial estimate of the feasibility of such a process. By adding a diesel-quality-fuel output to the process, the product value is increased significantly compared to a conventional BP. An input of 1000 kg h(-1) manure delivers approximately 30-38 kg h(-1) fuel and 38-61 kg h(-1) biogas. The biogas can be used to upgrade the biocrude, to supply the gas grid or for CHP. An estimated 62-84% of the biomass energy can be recovered in the biofuels.