Optimal synthesis of thermally coupled distillation sequences using a novel MILP approach

Abstract

This paper introduces a novel MILP approach for the design of distillation columns sequences of zeotropic mixtures explicitly including from conventional to fully thermally coupled sequences and divided wall columns with a single wall.The model is based on the use of two superstructure levels. In the upper level a superstructure that includes all the basic sequences of separation tasks and all the possibilities of heat exchange (condensers and reboilers). In the lower level an extended tree that explicitly includes all the alternatives for a given separation task (different thermal states and compositions of the feed to a given separation task). In that way, it is possible to a priori optimize all the possible separation tasks involved in the superstructure. A set of logical relationships relates the feasible sequences (upper level) with the optimized tasks in the extended tree resulting in a MILP to select the optimal sequence. Performance of the model in terms of robustness and computational time is illustrated with several examples.

Design and optimization of the levulinic acid recovery process from lignocellulosic biomass

“…On the other hand, it cannot be applied to the separation of azeotropic mixtures. Several rigorous methods have proposed, such as a sequential quadratic programming-based method implemented in Aspen Plus (Kiss and Suszwalak, 2012a), and a MILP approach based on the use of two superstructure levels (Caballero and Grossmann, 2014).…”

Application of the partially thermally coupled distillation flowsheets for the extractive distillation of ternary azeotropic mixtures

“…In some cases, PTCDCs decrease the energy consumption in the column boilers up to 20-30% compared to the conventional ED flowsheets [39][40][41][42] . Several authors have developed different approaches to the synthesis of distillation flowsheets with the partially thermally coupled flows for zeotropic mixture 34,[43][44][45][46][47][48][49][50] separation. There are only a few studies related to the synthesis of ED sequences with PTCDC.…”

Conceptual Design of Highly Integrated Processes – Optimization of Dividing Wall Columns

“…Shortcut models are applied for the preassessment of the different variants in process synthesis , , but are also a key element of most sequential design approaches, where they are applied as preprocessing step in order to initialize the DDoF of a rigorous simulation model . Most of the shortcut methods are based on the method of Underwood for the determination of the minimum vapor flow rate or minimum reflux ratio and the Fenske equation for the determination of the minimum number of equilibrium trays for simple columns.…”