CFD modelling and simulation of Nozzle reactor for fast Hydrothermal Liquefaction
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Hydrothermal Liquefaction is a promising technology for converting plant biomass directly to liquid with better fuel properties compared to traditional fast pyrolysis. The technology employs water, in subcritical conditions as reaction media, and therefore is very suitable for wet biomass feedstock including aquatic biomass and agricultural waste. Various challenges have to be overcome for this technology. From them, the major ones are corrosion, precipitation of inorganic salt and char and coke formation. These factors have been studied, being char and coke formation the most critical one, due to the obtaining of lower bio-oil yields and possible blockages in the process.This issue is solved mainly by means of the use of catalysts. However, fast heating rates obtained in capillarity reactors have been demonstrated to minimize the char and coke formation, with its correspondent optimization of the bio-oil yield. Thus, an alternative Hydrothermal Liquefaction process in which higher heating rates are achieved becomes an interesting matter of study.From this alternative fast Hydrothermal Liquefaction, the need of developing a plug-flow counter-current reactor for scaling up the continuous process has been identified. A reactor with these conditions, called nozzle reactor, has already been constructed and studied in the University of Nottingham, with the aim of obtaining a continuous hydrothermal synthesis of nanoparticles. The possibility of using a similar configuration to the nozzle reactor for performing the fast Hydrothermal Liquefaction process has been studied and experimentally demonstrated at NTNU.The aim of this thesis is designing a validated CFD model relevant for fast Hydrothermal Liquefaction able to simulate and analyze how the nozzle reactor works and the impact changing different parameters would have on it. Afterwards, a study for scaling up and industrializing the nozzle reactor could be performed.