Computers and Chemical Engineering 71 (2014) 52–66 Contents lists available at ScienceDirect Computers and Chemical Engineering j our na l ho me pa g e: www.elsevier.com/locate/compchemeng An MINLP model for the simultaneous integration of energy, mass and properties in water networks Arturo Jiménez-Gutiérrez a,∗ , Jonathan Lona-Ramírez a , José María Ponce-Ortega b , Mahmoud El-Halwagi c a Chemical Engineering Department, Instituto Tecnólogo de Celaya, Av. Tecnologico y Garcia Cubas, Celaya, Gto 38010, Mexico b Chemical Engineering Department, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich 58060, Mexico c Chemical Engineering Department, Texas A&M University, College Station, TX 77843, USA a r t i c l e i n f o Article history: Received 28 March 2014 Received in revised form 10 July 2014 Accepted 14 July 2014 Available online 22 July 2014 Keywords: Simultaneous optimization Water networks Energy integration Mass integration Property integration a b s t r a c t A model for the synthesis of water networks with a simultaneous integration of energy, mass and prop- erties is presented. The model is formulated within a mixed-integer nonlinear programming framework where the objective function accounts for the minimization for the total annual cost satisfying energy, mass and property constraints for the water streams involved in the network. To accomplish this task, a new superstructure is proposed, in which a first stage for energy integration before mixing streams was considered, followed by a mass and property integration network, and placing finally a second energy integration network. Within this approach, the optimization model identifies when a stream can be used as a hot or a cold stream as part of the energy integration. The proposed approach was applied to two case studies, and the results show that there are significant advantages for the simultaneous implementation of the energy, mass and property integration strategies. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Process integration tools have been used to improve the economic performance of production processes and to provide more sustainable structures. Proper management of energy and water resources can be achieved by the application of energy and mass integration techniques. Energy integration was noticeably sparked by the development of the pinch point methodology, through which targets for minimum heating and cooling requirements are established, followed by a network design that meets such targets (Hohmann, 1971; Linnhoff and Flower, 1978; Umeda et al., 1978). The development of mass integration techniques was started by an extension of pinch concepts (El-Halwagi and Manousiouthakis, 1989, 1990); thus, targets for fresh sources consumption and wastewater flowrates were first established, and a design that met those targets through the transfer of pollutants from a set of rich streams to a set of lean streams was carried out. Alternative structures were then developed for mass integration, considering process equipments as sinks to design direct recycle networks (El- Halwagi et al., 1996; El-Halwagi, 1997; El-Halwagi and Spriggs, 1998). Through this framework, a mass integration network with a proper allocation, generation, transformation, and separation of streams and chemical species within the process is achieved. Specific applications for the minimization of the use of water in chemical processes have been developed (Wang and Smith, 1994; Dhole et al., 1996; Polley and Polley, 2000; El-Halwagi et al., 2003; Hallale, 2002). An additional aspect to consider in mass and water integration networks was the fact that several environmental restrictions not only limit the concentration of chemical pollutants, but also the property levels that discharge streams pose to the environment, such as odor, color, and pH, among others. This gave rise to a new approach of mass integration based on properties (Shelley and El-Halwagi, 2000), which included the development of mixing rules based on property operators in order to estimate the resulting properties after mixing of streams. Such principles were used to develop methods based on pinch concepts for the design of networks with recycle, interception and process modifications based on properties (Eden et al., 2002; El-Halwagi et al., 2004; Kazantzi and El-Halwagi, 2005; Foo et al., 2006), as ∗ Corresponding author. Tel.: +52 461 611 7575x5577. E-mail address: arturo@iqcelaya.itc.mx (A. Jiménez-Gutiérrez). http://dx.doi.org/10.1016/j.compchemeng.2014.07.008 0098-1354/© 2014 Elsevier Ltd. All rights reserved.