MINIMUM UTILITY COST OF MASS-EXCHANGE NETWORKS WITH VARIABLE SINGLE-COMPONENT SUPPLIES AND TARGETS

Mass exchange network (MEN) synthesis is considered, with streams whos e supply and target compositions are allowed to vary between upper and lower bounds. The design task is to determine the minimum mass separa ting agent (utility) cost needed for the transfer of a component from the rich to the lean streams. The mathematical formulation of this syn thesis problem leads to a mixed integer nonlinear program (MINLP). Thi s program is shown to possess certain properties which, in turn, are u sed to develop a solution procedure. This procedure is guaranteed to c onverge to the global optimum. Two examples, illustrating that utility cost savings can be achieved over the fixed composition MEN synthesis problem, are discussed.