Heat Integration of Direct, Indirect, and Prefractionator Arrangements Using Multi-Effect Distillation Method in Separation of Ternary Mixtures

Distillation is the most known separation method in the industry, while consuming the highest energy in chemical industries. To separate a multi-component mixture, it is possible to use different arrangements, which choosing an appropriate arrangement plays an important role in the energy consumption of process. In this study, the separation of ternary mixtures of n-pentane, n-hexane, and n-heptane was investigated. At first, the direct, indirect, and prefractionator arrangements were used in order to the completely separation of all three components. Then, the multi-effect distillation method was employed for the heat integration of the three arrangements. For this purpose, a column distillation was operated at high pressure, while the other was run at low pressure. The condenser of the high-pressure distillation column and the reboiler of the low-pressure distillation column were removed, and the heat exchange between the vapor and liquid leaving the high-pressure and low-pressure distillation column was performed in a heat exchanger, respectively.The results indicated that the direct arrangement with heat integration using multi-effect distillation method had the lowest energy consumption. Therefore, it was chosen as the best arrangement. According to the results, the direct arrangement with heat integration using multi-effect distillation method was reduced energy consumption by ۴۷.۱۴% compared to the indirect arrangement without heat integration.

Keywords:

Separation , Heat-integration , Multi-effect , Distillation , Direct arrangement ,