Dynamic controllability investigation of an energy-saving double side- stream ternary extractive distillation process

Ao Yang, Tao Shi, Shirui Sun, Shun'an Wei, Weifeng Shen, Jingzheng Ren

Research output: Journal article publicationJournal articleAcademic researchpeer-review


The investigation of dynamic controllability for the double side-streams ternary extractive distillation (DSTED) is necessary due to its advantages in energy-efficient. However, the control strategy of the energy-saving DSTED scheme is unique and complex issues owing to the wobbly of side-stream flow rate. Herein, control strategy of the energy-saving DSTED scheme is explored for separating ternary azeotropic mixtures acetonitrile/methanol/benzene. Inspiring from the control strategy of the ordinary triple-column extractive distillation scheme, the fundamental control structure CS1 is firstly designed. The control scheme CS2 with feed/side-stream (F/SS) ratio and control structure CS3 with feedforward and F/SS are then investigated to achieve higher efficiency of process control. Finally, a robust control strategy CS4 with the ratio of reboiler duty and feed flow rate and without F/SS ratio is proposed to well maintain the product purities. Moreover, additional ±15% feed flow rate and composition disturbances are added in the CS4 to assess the stability and controllability of the energy-saving DSTED. Dynamic performances illustrate that the structure CS4 can handle as well as that of confronted ±10% disturbances when the large disturbances are occurred in the real chemical process.
Original languageEnglish
Pages (from-to)41-53
JournalSeparation and Purification Technology
Publication statusPublished - 15 Oct 2019


  • Ternary azeotropic mixtures
  • Dynamic control
  • Separation
  • Side-stream extractive distillation

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