Multi-objective optimization of a plug flow reactor using a divide and conquer approach

© 2017 Lower profit margins and tighter environmental constraints push chemical companies to search for sustainable development and operation. To ensure sustainable development and operation in practice, multiple and conflicting objectives (e.g., maximize production vs. minimize energy consumption) typically have to be optimized simultaneously. The frame of multi-objective optimization allows to systematically propose improvements and evaluate trade-offs between different objectives. Solving a multi-objective optimization problem yields a set of solutions called the Pareto front, in which no improvement can be made in one objective without worsening another objective. The posteriori analysis of this set by a smart filter aims to keep only the significant solutions for the decision maker who is interested in a specific level of trade-offs. However, this strategy suffers from the large overhead of insignificant solutions produced in the original set. This situation makes applying this strategy to the complex multi-objective optimal control problems time consuming. In this paper, the smart filter by Mattson et al. (2004) is compared to a novel Divide and Conquer (D&C) algorithm to obtain a Pareto front with adaptive resolution for a case study of a plug flow reactor. The new algorithm depends on obtaining the Pareto front recursively while terminating the exploration of a Pareto front segment as soon as an insignificant point is found. It is shown that the D&C algorithm produces representations with similar quality to the smart filter with higher speed and a more intuitive trade-off oriented solution procedure.

Publication year:2017

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Authors from:Higher Education