Automatic Design and Optimization of Column Sequences and Column Stacking Using a Process Simulation Automation Server

Abstract

Simulation−optimization is applied to determine nearly optimal process designs in column sequencing and stacking problems using a simulated annealing algorithm (SAA) in the client (MATLAB) and a single distillation column in the server (Aspen Plus). Each column in every sequence is optimized separately, and the total cost of each sequence is calculated. This method benefits from both the rigor of column modeling in a process simulator and the flexibility of implementing sequential procedures and derivative-free optimization in a procedural programming language. Using this method, a single column can be optimized within 6 min of computer time. Furthermore, when stacking rules and available utilities are specified, a nearly optimal heat-integrated distillation column sequence can be designed automatically. Results are illustrated using two case studies of column sequencing problems.

Automatic Column Sequencing and Optimization for Homogeneous Azeotropic Mixtures

“…The optimization is implemented using the Aspen Plus ActiveX automation server as the server with Python as the client so that simulation can be carried out in Aspen Plus and optimized by the SA algorithm coded in the client automatically. The method of Ni and Ward takes minutes for each column, which shows that it is an efficient way to identify the optimal column designs. For the extractive distillation systems, the method is capable of considering six design variables although the optimization takes several hours.…”

“…The sequential single-column simulation method developed by Ni and Ward is used to design and optimize the ordinary columns. In this method, the ordinary columns in each sequence are torn into a set of single columns, and the impurities in the product streams are neglected when modeling the succeeding column.…”

“…Once a feasible split was identified, ordinary distillation columns were designed and optimized using the method described by Ni and Ward. 31 Two-column extractive distillation subsystems were designed using the method of Yang and Ward 32 for the separation of binary azeotropes. Individual columns were simulated in Aspen Plus using the RADFRAC column model.…”

Optimization of Distillation Sequences with Nonsharp Separation Columns

“…The DSTWU module uses the Winn-Underwood-Gilliland (WUG) method for a short-cut. The Winn equations are cited as Equations (6) and (7).…”

“…Xu et al [5] improved 0-1 matrices into code matrices, but the information conveyed by code matrices is insufficient to describe the details of columns. Ni et al [6] used a process simulation automation server to realize the optimization of heat-integrated sequences at both the sequence level and the column level. Proios et al [7] proposed an improved generalized modular framework that can overcome the structural complexities of thermally-coupled columns, including dividing wall columns, through systematic and highly detailed structural models.…”