Robustness of steady state recycling chromatography with an integrated solvent removal unit

• Robustness of recycling chromatography with a solvent removal unit is analysed.
• The Unified Design approach was applied for selecting robust operating conditions.
• The shape of the operating space depends strongly on the solvent removal capacity.
• Robustness can be improved by adjusting the solvent removal rate or the cut times.

The robustness of a hybrid separation process where the performance of mixed-recycle steady state recycling chromatography is enhanced by integrating it with a solvent removal unit is analysed theoretically and by means of numerical simulations. The equilibrium theory of chromatography is applied to derive equations for boundaries of feasible operating parameters in such a hybrid process. Visualization of the feasible operating parameter ranges helps in analysing the influence of various physical and process parameters of robustness of an operating point. It is observed that process robustness can be improved by adjusting the solvent removal capacity or the cut times. When the solvent removal capacity increases, the region of feasible cut times becomes narrower due to increased non-linearity of the system. This makes it more difficult to maintain robust operation.