Moeen EL BAST thesis defense

In this thesis, a design of a continuous biomass hydrothermal liquefaction system is proposed. After a study of the different existing hydrothermal liquefaction processes and the different mechanisms involved, models simulating the different thermochemical phenomena involved have been proposed. These phenomena were studied at the scale of a 1L batch reactor and modeled using COMSOL Multiphysics software. To do this, an experimental campaign is carried out on the reactor, starting from the heating of the empty reactor and ending with a complete elementary chemical reaction; supercritical transesterification of rapeseed oil. The experimental curves of temperature at different places in the reactor and of pressure helped to calibrate different models of heat diffusion, pressurization, evaporation and transport of species. Finally, the chemical kinetics model of the supercritical lipid transesterification reaction was experimentally validated using the conversion rate as a comparison parameter. The maximum relative error on the different modeled parameters is less than 6%. The validated batch reactor model helps in the design of a continuous system. A process combining a stirred reactor (CSTR) and a piston reactor (PFR) has been proposed. After scanning the different temperature and flow rate ranges, a 1 L CSTR and a 2.44 m, 1 cm diameter PFR were chosen to handle a flow rate of 10 L/h of reactant mix. After the dimensioning of the various organs, a complete and integrated system was proposed.