Chapter Three - Synthesis of Mass-Exchange Networks: A Graphical Approach

Abstract

This chapter defines the problem of synthesizing mass-exchange networks (MENs), discusses its challenging aspects, and provides a graphical approach for the synthesis of MENs. There are several sources from which mass have to be removed, and many mass separating agents can be used for removing the targeted species. Therefore, adopting a systemic network approach can provide significant technical and economic benefits. In this approach, a mass-exchange system is selected and designed by simultaneously screening all candidate mass exchange operations to identify the optimum system. The “targeting approach” tool is used to systematically address the MEN synthesis task. In the context of synthesizing MENs, two useful targets can be established: minimum cost of mass-separating agents (MSAs) and minimum number of mass exchanger units. The concept of corresponding composition scales can be used in synthesizing MENs. It can be used for incorporating thermodynamic constraints of mass exchange by establishing a one-to-one correspondence among the compositions of all streams for which mass transfer is thermodynamically feasible. Another graphical approach for the synthesis of MENs is the pitch diagram. It helps in constructing a rich composite stream represents the cumulative mass of the pollutant lost by all the rich streams.