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The mathematical technique presented in this work deals with one step design of single-and multicontaminant batch water-allocation network (WAN), where batch production, water-reuse subsystems, and wastewatertreatment subsystems are all taken into account. In the first place, a flexible schedule model combining the merits of discrete and continuous time formulations is introduced to integrate batch production and WAN. Then, two novel state-time-space (STS) superstructures incorporating all basic elements (i.e., states, tasks, equipment, and time) are adopted to capture all production schemes and batch WAN configurations. Specifically, by adding novel components in the original superstructure, a series of optimal network structures with multistage splitting and mixing options which have never been contained within previous superstructure can be easily generated. Finally, a reliable optimization strategy, where deterministic and stochastic searching techniques are combined, is suggested to deal with the resulting mixed integer nonlinear programming (MINLP) model.Two illustrative examples are presented to demonstrate the effectiveness of the proposed approach.

Part 1 of the series proposes a multiscale state-space superstructure for interplant water-allocation and heatexchange networks (IWAHENs) design with direct and indirect integration schemes in fixed flow rate (FF) processes (Zhou, R. J.; Li. L. J.; Dong, H. G.; Grossmann, I. E. Synthesis of Interplant Water-Allocation and Heat-Exchange Networks. Part 1: Fixed Flowrate Processes. Ind. Eng. Chem. Res. 2012, 51, 4299). Based on the same superstructure, part 2 of this series extends the IWAHEN integration methods to fixed contaminant-load (FC) processes as well as integration of FF and FC processes. The integrations are performed by solving the corresponding mixed-integer nonlinear programming (MINLP) models based on the multiscale state-space superstructure. Several relevant examples, including both direct and indirect integrations for IWAHENs, are presented to illustrate various aspects of the proposed approach.

This paper is part 1 of a series dealing with the design of integrated interplant water-allocation and heat-exchange networks (IWAHENs), a special case of interplant network synthesis with multiple physical properties. Traditionally, the tasks of optimizing water-allocation networks (WANs) and heat exchange networks (HENs) were either performed individually or studied within a single plant. In this paper, a novel multiscale state−space superstructure is developed to capture all possible network configurations for the fixed flow rate (FF) IWAHEN designs with both direct and indirect integration schemes. In addition, our model has been simplified to deal with the interplant HEN design where the optimal utility network can be determined simultaneously. By properly addressing the interactions between different plants as well as the WAN and HEN subsystems, lower total annualized cost (TAC) can be obtained in all examples by solving the corresponding mixed-integer nonlinear programming (MINLP) model.

The mathematical model developed in this paper deals with simultaneous synthesis of the integrated separation network, where both mass separating agents (MSAs) and energy separating agents (ESAs) are taken into account. The proposed model formulation is believed to be superior to the available ones. Traditionally, the tasks of optimizing ESA-based and MSA-based processes were either performed individually or studied on a heuristic basis. In this work, both kinds of processes are incorporated into a single comprehensive flowsheet and a novel state-space superstructure with multi-stream mixings is adopted to capture all possible network configurations. By properly addressing the issue of interactions between the MSA and ESA subsystems, lower total annualized cost (TAC) can be obtained by solving the corresponding mixed-integer nonlinear programming (MINLP) model. A benchmark problem already published in the literature has been investigated to demonstrate how better conceptual designs can be generated by our proposed approach.