Novel Reformulations for Modeling Uncertainty and Variations in a Framework for Chemical Process Design

In this work, we present a framework to support designers in the early-stage screening and design of chemical processes under uncertainty. The suggested framework is a stepwise approach which identifies: (1) if structural design proposals are structurally feasible, (2) the necessary and most cost-efficient overdesign of equipment size to allow for steady-state flexible operation, and (3) a basis to compare different structural design proposals with respect to a given objective. In contrast to previous work, the suggested framework utilizes advanced modeling of the expected uncertainty space to allow for considering dependencies in the uncertain parameters as well as independent operating periods. Theoretical examples illustrate how the advanced modeling can enable a better representation of the actual flexibility of a process compared to using more traditional representations of the uncertainty space. To illustrate the benefits of the proposed framework, the paper also presents an industrial case study of a heat exchanger network retrofit.