Energy-saving design and optimization of pressure-swing-assisted ternary heterogenous azeotropic distillations
Authors: Lianjie Wu, Kun Lu, Qirui Li, Lianghua Xu, Yiqing Luo, Xigang Yuan
A huge amount of energy is always consumed to separate the ternary azeotropic mixtures by distillations. The heterogeneous azeotropic distillation and the pressure-swing distillation are two kinds of effective technologies to separate heterogeneous azeotropes without entrainer addition. To give better play to the synergistic energy-saving effect of these two processes, a novel pressure-swing-assisted ternary heterogeneous azeotropic distillation (THAD) process is proposed firstly. In this process, the ternary heterogeneous azeotrope is decanted into two liquid phases before being refluxed into the azeotropic distillation column to avoid the aqueous phase remixing, and three columns' pressures are modified to decrease the flowrates of the recycle streams. Then the dividing wall column and heat integration technologies are introduced to further reduce its energy consumption, and the pressure-swing-assisted ternary heterogeneous azeotropic dividing-wall column and its heat integration structure are achieved. A genetic algorithm procedure is used to optimize the proposed processes. The design results show that the proposed processes have higher energy efficiencies and lower CO2 emissions than the published THAD process.
