Towards on energy-saving and cost-reducing heterogeneous azeotropic distillation process for separating n- butanol/isobutanol/water

N-butanol, isobutanol, water can form a ternary azeotropic mixture, which is often separated by special distillation methods in the chemical industry. In our previous work, an efficient extractive distillation process was proposed for the separation of this mixture. This work focuses on developing another efficient heterogeneous azeotropic distillation (HAD) process for the same goal. Firstly, according to thermodynamic analysis, a basic HAD process is proposed and optimized to minimize both the total annual costs (TAC) and CO2 emissions. Three HAD enhanced processes using dividing-wall column, vapor recompression heat pump and pressure-swing thermal couple distillation are designed and heuristically optimized. Finally, the performance of these schemes is analyzed from four aspects: economy, environment and exergy (3E). The results demonstrate that, in comparison to the basic process, the enhanced process HADWC-HPTC reduces TAC by 27.44 %, CO2 emissions by 80.01 %, and exergy loss by 62.57 %.