Effects of flow-rate ratio on startup and cyclic steady-state behaviors of simulated moving bed under linear conditions

The influence of the flow-rate ratio (m-value) on the startup and the cyclic steady-state performance of the simulated moving bed (SMB) process were studied under the condition of a fixed feed flow rate. Each system was evaluated from the viewpoint of four performance parameters (major product concentration, purity, eluent consumption, and productivity). Flow-rate ratios of zones II and III (m2 and m3) played key roles in the startup and cyclic steady-state behaviors of the performance parameters compared to m-values of zones I and IV (m1 and m4) in the four-zone SMB process. However, the performance parameters were steeply changed near the operating boundaries of m1 and m4 even though their variation was smaller than the results from m2 and m3. In addition, the effects of m1 and m4 on the major product concentration were substantial in the operating range. The startup periods of both product concentrations were increased as the operating point in the triangle region became far from the diagonal in terms of m2 and m3. On the other hand, the variation of m1 and m4 could lead to a change in performance without any adjustment to the startup period.