ETD

• Acetosolv
• Cellulose
• Pulping
• Recovery
• Thermal separation

An innovative method has been developed and patented, which modifies the acetosolv process, for obtaining cellulose through a combined pulping and bleaching step. The process uses an aqueous solution of acetic acid, catalysed by H3PO4 and H2O2, in strong excess compared to the biomass, operating at atmospheric pressure and temperatures close to 100°C. This thesis examines the topic of reagent recovery for the construction of a pilot plant. Laboratory tests were carried out in order to characterize the effluents to be treated, the liquid/vapour equilibrium, the recoverable fractions and the viscosity of the residues obtained. The sizing of a vacuum thermal separation unit (0.12 bar) was carried out in order to limit the formation of organic solids. This equipment, consisting of a forced circulation evaporator, operates continuously for 214 kg/h of effluent and allows the recycling of at least 95% of the initial acetic acid, in aqueous solution. The organic residue is sent to combustion, covering the thermal demand of the evaporator by more than 72%.