A novel graphical approach for mass exchange networks using composition driving force

Abstract

Raw materials are considered as a corner stone for both chemical and process industries. Raw materials efficient utilization and usage within the process saves a lot. Mass integration is the most competent path to minimize the economic and environmental losses, by minimizing both the amounts of external mass separating agents and waste disposal. Mass exchange networks or MENs is the tool used to apply this integration. This article presents a new graphical approach, based on the composition driving force, to analyse the mass integration and exchange networks. The new approach is illustrated graphically, and can be applied on existing and new mass networks. The new graphical approach is constructed based on the Pinch Analysis Principle where the lean stream compositions are plotted on the X-axis, while the composition driving forces for each exchanger are plotted on the Y-axis. The performance of MENs is evaluated and analysed in terms of the composition driving force (CDF) inside the mass exchanger. In addition to be the main motive to transfer the composition from rich stream to lean stream, composition driving force is also involved in the calculation of the number of theoretical plates, consequently affecting the cost. Each mass exchanging unit is represented in this graph as a straight line whose slope is related to the mass flow rates of both rich and lean streams and its length is related to the mass load transferred within the exchanger. The CDF is divided into five regions, based on the pinch analysis principles to analyse and perfectly locate the mass exchangers. The new graphical approach is applied to existing MENs to enhance their actual performances by minimizing wastes disposal and external separating agents and accomplish the mass targets defined by the Pinch Analysis Principles.