Molecular tracking: A novel approach for multicomponent distillation column design

This paper proposes a new systematic methodology to design a distillation column with middle products (side-draw) for ideal ternary mixtures, where the middle boiling component is present at trace concentrations. The method uses a molecular tracking concept, which uses a probability function based on the thermodynamic properties of the system.

The probability function expresses the possibility of upward/downward movement of a single molecule on a tray inside a column. The advantage of this method compared to other existing methods is in its capability to quickly and efficiently provide a feasible solution without relying on rigorous optimization or trial/error approaches.

In addition, the inherently graphical nature of the methodology allows engineers to get an intuitive understanding of the movement of the often-complicated middle product. The methodology is demonstrated on an ideal ternary mixture of benzene and p-xylene with toluene as the trace middle boiler, where the results obtained through the molecular tracking were validated against a rigorous process simulation.