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

A new method for the synthesis of mass exchanger networks for multi-period operations is presented in this paper. The new technique which is called multi-period interval based MINLP superstructure (MIBMS) for mass exchange network synthesis (MENS) is adapted from the interval based MINLP superstructure for MENs presented by Isafiade and Fraser (2008). Process parameters such as supply and target compositions and flowrates of streams can vary over a specified range due to environmental or economic reasons. 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 in this paper can be unequal. Themaximum 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. It should be known that this technique applies to multi-period problems where the process parameters for each period of operation as well as the duration are specified. The method does not handle scenarios where the process parameters are uncertain. The new technique is applied to three examples.