TABLE OF CONTENTS The mass exchange pinch analysis (El-Halwagi and Manousiouthakis 1989a) provides a holistic and systematic approach to synthesizing MENs. It also enables the identification of rigorous targets such as minimum cost of MSAs. The first step in the analysis is to develop an integrated view of all the separation tasks for the rich streams. This can be achieved by developing a composite representation of mass exchanged from all the rich streams. Mass of targeted species removed from the i th rich stream is given by:
By plotting mass exchanged versus composition, each rich stream is represented as an arrow whose tail corresponds to its supply composition and its head to its target composition. The slope of each arrow is equal to the stream flowrate. The vertical distance between the tail and the head of each arrow represents the mass of targeted species that is lost by that rich stream. In this representation, the vertical scale is only relative. Any stream can be moved up or down while preserving the same vertical distance between the arrow head and tail and maintaining the same supply and target compositions. A stream cannot be moved left or right, otherwise stream composition will be altered. A convenient way of vertically placing each arrow is to rank the rich streams in ascending order of their targeted composition then we stack the rich streams on top of one another, starting with the rich stream having the lowest target composition. Once the first...
