(114f) Optimization of Ternary Simulated Moving Bed Separation by Nonlinear Programming

Simulated moving bed (SMB) chromatography has been widely studied in past and there have been various operating schemes proposed such as PowerFeed and VARICOL for efficient separation of binary mixtures. SMB is a promising option of separation because of its capability to achieve efficient separation even when the components differ very little in terms of affinity towards stationary and mobile phase. However, separation of a ternary mixture using SMB is still a major drawback of this technology. Although, many different strategies [1, 2, 3, 4] have been proposed, previous studies have rarely performed comprehensive investigations for finding the best ternary separation strategy from various possible alternatives.

Our study addresses this issue by adopting a systematic nonlinear programming approach. The performances of several systems [1, 2, 4], in terms of throughput obtained and amount of desorbent consumed, are compared at optimal conditions. The optimization problem, constrained by partial differential algebraic equations model, is fully discretized both in temporal and spacial domain. The resulting nonlinear programming problem is handled by IPOPT 3.0, an interior point solver. These results are obtained for linear adsorption isotherms considered in Mata et al. [3]. We finally propose a superstructure encompassing many of the operating schemes proposed in literature for separation of a ternary mixture. The superstructure approach has a potential to find more advantageous operating scheme then the existing operating schemes.

[1] A. Nicolaos, L. Muhr, P. Gotteland, R. Nicoud, and M. Bailly. Application of equilibrium theory to ternary moving bed configurations (four+four, five+four, eight and nine zones): I. Linear case. Journal of Chromatography A, 908:71–86, 2001.

[2] A. S. Kurup, K. Hidajat, and A. K. Ray. Comparative Study of Modified Simulated Moving Bed Systems at Optimal Conditions for the Separation of Ternary Mixtures under Nonideal Conditions. Ind. Eng. Chem. Res., 45:3902–3915, 2006.

[3] V. G. Mata and A. E. Rodrigues. Separation of ternary mixtures by pseudo-simulated moving bed chromatography. Journal of Chromatography A, 939:23–40, 2001.

[4] T. Masuda, T. Sonobe, F. Matsuda, and M. Horie. Process for fractional separation of multi- component fluid mixture. US Patent No. 5,198,120, 1993.