Optimization Study of Hydrothermal Liquefaction Sewage Sludge to Biocrude Oil in Continuous Multiphase Plug Flow Reactor

This paper provides an optimization analysis of the hydrothermal liquefaction (HTL) process of sewage sludge to biocrude oil in a continuous plug-flow reactor. The increase in flow rate led to enhanced swirling flow, which significantly improved convective heat transfer. The composition and yield of biocrude oil produced in the process (HTL) can vary significantly depending on the type of feedstock used. Using process simulation principles and a kinetic model, this study thoroughly evaluated the mass and energy balance of the HTL reaction, considering heat and mass momentum exchange in a multiphase system. Therefore, it is useful to use a transient flow model to determine the influence of process parameters on optimization. A parametric study with multiphase profiles along the reactor axis allowed tracing of interphase flow trajectories for optimal conditions in order to maximize the process efficiency of biocrude oil production. Through optimization of process parameters, there was a significant improvement in the conversion of sewage sludge to biocrude oil in the continuous HTL process. The optimal conditions were where the reaction mass maintained in the liquid phase enabled the stabilization of process parameters, preventing evaporation and heat loss by increasing the energy process efficiency.