Biocrude Production from Hydrothermal Liquefaction of Chlorella: Thermodynamic Modelling and Reactor Design

Abstract

Hydrothermal liquefaction can directly and efficiently convert wet biomass into biocrude with a high heating value. We developed a continuous hydrothermal liquefaction model via Aspen Plus to explore the effects of moisture content of Chlorella, reaction pressure and temperature on thermodynamic equilibrium yields, and energy recoveries of biocrude. We also compared the simulated biocrude yield and energy recoveries with experiment values in literature. Furthermore, vertical and horizontal transportation characteristics of insoluble solids in Chlorella were analyzed to determine the critical diameters that could avoid the plugging of the reactor at different flow rates. The results showed that the optimum moisture content, reaction pressure, and reaction temperature were 70–90 wt%, 20 MPa, and 250–350 °C, respectively. At a thermodynamic equilibrium state, the yield and the energy recovery of biocrude could be higher than 56 wt% and 96%, respectively. When the capacity of the hydrothermal liquefaction system changed from 100 to 1000 kg·h−1, the critical diameter of the reactor increased from 9 to 25 mm.

Multiphase Numerical CFD Simulation of the Hydrothermal Liquefaction Process (HTL) of Sewage Sludge in a Tubular Reactor

“…Joshi et al [16] developed a 3D CFD model to simulate the influence of process parameters on suspension flow and solid particle transport, determined by the Prandtl number. However, previous studies mainly focused on predicting the HTL conversion efficiency of microalgae suspension in continuous tubular reactor mode [15][16][17].…”

Multiphase Numerical CFD Simulation of the Hydrothermal Liquefaction Process (HTL) of Sewage Sludge in a Tubular Reactor

“…Joshi et al developed a 3D CFD model to simulate the influence of process parameters on suspension flow and solid particle transport determined by the Prandtl number. However, previous studies mainly focused on predicting the HTL conversion efficiency of microalgae suspension in continuous tubular reactor mode [17]. Recently, few studies have been reported on the HTL process in continuous reactors on a pilot scale.…”

Thermodynamics of the hydrothermal synthesis of xonotlite

“…The thermodynamic model of hydrothermal reactions can assist studying the synthesis process, and has been widely adopted in the geology and the chemical industries [30][31][32][33][34][35][36]. Ma et al [37] studied the thermodynamics of hydrothermal synthesis of xonotlite from potassium silicate and Ca(OH) 2 , and provided theoretical guidance to the experimental process.…”