Energetic assessment of lignin extraction processes by simulation

Abstract

Abstract The energetic requirements of several processes for high-purity lignin production from lignocellulosic waste streams has been studied in this work, based on simulation analysis performed with experimental data. The introduced variables were: two different raw materials (almond shell and olive tree pruning), the use of a pre-treatment stage and the application of two different sulphur-free delignification methods (organosolv and soda processes) with their subsequently lignin precipitation steps. In total, four scenarios were approached and assessed in terms of desirable product yields, water and chemical consumptions and energetic duties. Results showed a more efficient process when almond shell was used as raw material. In terms of the delignification process, organosolv method required a much lower quantity of chemicals due to the recycle and recirculation of the solvent (ethanol). The energy consumption associated to this recycle implied an increase of 18-12 % in the total energy consumption. On the other hand, lignin product yield was higher with soda process although its chemical consumption was found to be much higher, in terms of soda and sulfuric acid requirements.