Interval Based MINLP Superstructure Synthesis of Multi-Period Mass Exchange Networks

A new method for the synthesis of mass exchanger networks for multi-period operations is presented in this paper. The new method which is called multi-period interval based MINLP superstructure (MIBMS) is adapted from the interval based MINLP superstructure for mass exchanger networks (MENs) presented by Isafiade and Fraser (2008). Parameters such as supply and target compositions and flowrates of streams can vary over a specified range. In this paper, the IBMS model for MENS is modified to handle variations in the aforementioned set of parameters by including the index 'p' in the IBMS model and using the maximum area approach in the objective function as presented by Verheyen and Zhang (2006) for multi-period heat exchanger networks synthesis (HENS). The index 'p' represents each period of operation which can be unequal. The maximum area approach ensures that each mass exchanger connecting the same pair of streams in more than one period is able to transfer mass in such streams for all the periods. This technique simplifies the model unlike the flexibility or stream bypass approach, as used in other studies, which is time consuming. The new technique is applied to one example adapted from the literature.