Theoretical analysis of steady state recycling chromatography with solvent removal

Abstract

The possibility to enhance the process performance of steady state recycling (SSR) chromatography by removing solvent was investigated in the framework of the equilibrium theory. A method was developed to choose a priori the relevant cut times corresponding to arbitrary purity constraints and to predict the steady state of the process without performing dynamic simulations. The amount of fresh feed introduced per cycle and the injection width were identified as the only free operating parameters. A relationship was derived between the amount of fresh feed and the solvent removal capacity required to achieve the chosen purities. The performance of three different process configurations was analyzed: solvent removal applied to (I) the fresh feed, (II) the recycle fraction, and (III) their mixture. It was found that solvent removal facilitates treating more fresh feed per cycle than is possible in a conventional SSR process. In addition, it was shown that the three SSR-SR configurations have identical performance with the same operating parameters. In contrast, the configurations differ with respect to the maximum amount of fresh feed that can be processed per cycle, as well as to the range of feasible injection widths. It was shown that SSR with solvent removal can yield higher productivity and lower eluent consumption than an optimized batch chromatography process that employs solvent removal.