As an important chemical
raw material, styrene has a high price
because of its high energy consumption for separation. This article
focuses on the styrene separation unit in a practical propylene oxide/styrene
monomer process, and divided wall columns (DWC) are used for process
optimization. Four DWC models are evaluated in terms of both economics
based on the minimum total annual cost (TAC) and operability based
on degrees of freedom. Differential evolutionary (DE) algorithms are
used to optimize the parameters for each case study. In the process
of finding the minimum TAC, the traditional DE often falls into local
solutions and has low efficiency. In order to solve this problem,
we propose chaotic sequences in DE algorithms to generate variables
with ergodicity, which improves the optimization efficiency. Compared
with the conventional process, Wright’s fully thermally coupled
DWC (FTC) and Agrawal’s liquid-only transfer DWC (ALT) can
save 21.36 and 10.14% TAC, respectively, but ALT has 2 more degrees
of freedom than FTC. The FTC has the best economic efficiency, while
the ALT strikes a balance between operability and economics.