Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (7): 1891-1897.doi: 10.1016/j.cjche.2020.05.005

• Process Systems Engineering and Process Safety • Previous Articles     Next Articles

Vapor recompressed dividing-wall distillation columns: Structure and performance

Lijing Zang, Kejin Huang, Yang Yuan, Xing Qian, Liang Zhang, Haisheng Chen, Shaofeng Wang   

  1. College of Information Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
  • Received:2019-11-12 Revised:2020-04-20 Online:2020-07-28 Published:2020-08-31
  • Contact: Kejin Huang
  • Supported by:
    We acknowledge the financial financial support from National Natural Science Foundation of China (21878011; 21676011; 21808007).

Abstract: Due to the topological structure of double columns and multiple separating sections in dividing-wall distillation columns (DWDCs), the development of vapor recompressed dividing-wall distillation columns (DWDC-VRHPs) represents a challenging issue with great complexities and tediousness. For the separations of light-component dominated and wide boiling-point ternary mixtures, because the purification of the light-component from the intermediate-and heavy-components incurs the primary energy dissipation, the application of vapor recompressed heat pumps (VRHP) should be aimed to reduce the irreversibility and this leads to the generation of the optimum topological structures of the DWDC-VRHPs, i.e., a DWDC plus a two-stage VRHP. The first-stage VRHP is to preheat feed, not only taking the advantages of the small temperature elevation available but also favoring the mass transfer between the vapor and liquid phases through feed splitting. The second-stage VRHP is to reduce further separation irreversibility. The philosophy can be applied to any DWDCs no matter where the dividing wall locates. Two case studies on the separations of ternary mixtures of benzene, toluene, and o-xylene and n-pentane, n-hexane, and n-heptane demonstrate the economic optimality of the proposed DWDC-VRHPs and reveal the inherent interplay between internal and external process integration.

Key words: Dividing-wall distillation column, Light-compoment dominance, Vapor recompressed heat pump, Process design, Process operability