ABSTRACT
ABST R AC T In designing and operating any water network, a typical issue that must be addressed is concerned with the uncertain process conditions. A systematic procedure is proposed in this paper to enhance their operational exibility. Specically, two design options have been investigated, i.e., (1) relaxation of the allowed maximum freshwater consumption rate in the nominal design and (2) installation of auxiliary pipelines and/or elimination of existing ones. The exibility index model proposed by Swaney and Grossmann (1985) has been modied and formulated in a generalized format to evaluate the impacts of introducing various modications into a given network. Since this model is a Mixed Integer NonLinear Program (MINLP),
CONTENTS
Introduction ......................................................................................................... 204 Problem Statement ............................................................................................. 205 Generalized Flexibility Index Model ................................................................ 206
Superstructure ............................................................................................ 206 Complete Model Formulation.................................................................. 206 Initialization Procedure ............................................................................. 207
A Simple Example .............................................................................................. 207 Attach Auxiliary Pipeline(s) ..................................................................... 209 Relax Upper Bound of Freshwater Usage .............................................. 210
Conclusions .......................................................................................................... 211 Acknowledgments .............................................................................................. 211 References ............................................................................................................. 211
it is in general very difcult to reach the global optima in the iterative solution processes. A simple and effective initialization procedure has also been devised in this work to facilitate successful convergence. Finally, the effectiveness of the proposed approach is demonstrated with an example in this paper.
