Combined operation of outlet streams swing with partial-feed in a simulated moving bed

The operational strategy of outlet streams swing (OSS) operation combined with partial-feed (PF) operation, OSS-PF, was studied under the constraint of maximum allowable pressure and flow-rate. Its separation performance and dynamic behavior were compared with those of OSS operation and conventional simulated moving bed (SMB) chromatography. During OSS-PF operation, the switching period consisted of two steps; raffinate was produced during the closed condition of extract node and feed node in the first step, while extracts were produced and feeds were injected during the closed condition of raffinate node in the second step. As a result, OSS-PF operation could be performed under the allowable maximum flow-rate in the corresponding conventional SMB without generating an additional pressure drop at the adsorbent bed, which was different from OSS operation. OSS-PF operation successfully improved the separation performance of the conventional SMB with regard to extract purity, raffinate recovery and raffinate productivity with equivalent eluent consumption. The step ratio during a switching period worked as one of important operating variables in separation performance. The dynamic behavior of OSS-PF operation was analyzed and compared with that of OSS and conventional SMB using simulated concentration profiles in the fluid phase.