17 th European Symposium on Computer Aided Process Engineering – ESCAPE17 V. Plesu and P.S. Agachi (Editors) © 2007 Elsevier B.V./Ltd. All rights reserved. Design of non-isothermal Process Water Networks Miloš Bogataj, a Miguel J. Bagajewicz b a Faculty of Chemistry and Chemical Engineering,University of Maribor Maribor SI- 2000, Slovenia, milos.bogataj@uni-mb.si b School of Chemical,Biological and Materials Engineering,University of Oklahoma, Norman, OK, 73019, USA, bagajewicz@ou.edu Abstract Despite the fact that many methods have been developed for the optimization of process water networks, solving the problem simultaneously considering heat recovery has rarely been addressed. This paper presents a new approach for the simultaneous synthesis and optimization of heat integrated water networks. The procedure is based on mixed integer non-linear mathematical programming (MINLP). A new superstructure for heat exchanger network (HEN) synthesis capable of exploiting unique features of water networks, like non-isothermal mixing of different streams, thus providing potentially more cost-effective solutions, is proposed. An example is presented to illustrate the synthesis of heat integrated water networks using the proposed approach. Keywords: water networks, wastewater minimization, heat integration, MINLP, HEN synthesis, process synthesis. 1. Introduction Different methods, rooted in conceptual design or mathematical programming, have been developed for water minimization as well as for the heat exchanger network (HEN) synthesis problem. The reader is referred to Bagajewicz (2000) for a comprehensive review of technologies developed to solve the water minimization problem and to Furman and Sahinidis (2002) for a review of the HEN synthesis technologies.