(721a) Characterization of Flow and Heat Transfer Parameters in a Continuous Flow Hydrothermal Liquefaction Reactor

Hydrothermal liquefaction (HTL) has been regarded as one of most promising wet-biomass processing techniques. Using subcritical water (270-350 ºC and 8-20 MPa), HTL converts biomass-derived macromolecules into energy-dense bio-crude oils, which can be upgraded into liquid biofuels using suitable catalysts. Developing continuous reactors is required prior to process commercialization, because of higher oil productivity and lower labor cost in a steady-state, continuous reaction systems. In this study, a supercritical fluid flow reactor was transformed and modified into a continuous plug-flow reactor for algae HTL, and preliminary tests were carried out to evaluate its performance. Various types of microalgae with different solids loadings (1.5-5 wt.%) were run under different operating conditions for more than 4 hours per run to test bio-crude oil productivity, dual filter cycling frequency, maximum solids loading tolerance, incidence of pressure spiking and clogging, and process safety and control. The theoretical residence time distribution was measured using phenol under 350 °C and 18 MPa. A variety of characterization methods were adopted for the HTL liquid products, such as Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS) and gas chromatography mass spectroscopy (GC/MS) for analyzing bio-oil chemistry, and oxy-combustion calorimetry and elemental analysis (CHNS) for setting up mass and energy balances in this continuous biomass-conversion process. Comprehensive results will help verify the technical feasibility of running wet biomass in this modified continuous reactor.