Simultaneous Control of Product and Feed Streams for High Performance in Simulated Moving Bed Chromatography

Simulated Moving Bed (SMB) Chromatography has been considered as an important separation process due to its effective separation efficiency. Therefore, it has been widely used in various industries including petrochemicals, fine chemicals, pharmaceuticals and biomaterials. To improve the SMB performance, many operating strategies using stream flow control have been reported. However, they often generate significant flow and pressure fluctuations during a switching period. Since such harsh flow and pressure variation can lead to damaging packed adsorbents and system, some operating conditions can’t be acceptable for real fields even though theoretical separation performance is high.

In the study, a novel operating strategy, SimCon operation, was developed to improve SMB performance. The SimCon operation controlled simultaneously product outlet streams and a feed inlet stream to reduce the flow and pressure fluctuations. It consisted of initial, middle, and last steps in a switching period. The extract and feed ports were closed in an initial step and the raffinate port was closed in a last step. Due to three sub-divided steps in a switching period, two additional operating variables were introduced: middle step time and middle length. In the SimCon operation, the control of feed inlet stream could keep total pressure drop from exceeding the maximum allowable pressure drop due to lessening the internal flow rate fluctuations by the control of product outlet streams. The performance of SimCon operation was compared with the corresponding conventional SMB and other stream control strategies in terms of purity, recovery, productivity and eluent consumption. The SimCon operation showed better performance parameters even under maximum allowable pressure drop condition. The SimCon operation was proved as one of practically applicable operating strategies with high performance.