Design of Simulated-Moving-Bed Chromatography with Enriched Extract Operation (EE-SMB):  Langmuir Isotherms

A variation of the simulated-moving-bed (SMB) operation, called Enriched Extract SMB (EE-SMB), is investigated, in which a portion of the extract product is concentrated and the resulting enriched stream is re-injected into the SMB at that same point, i.e., at the inlet of section 2. This operation has been recently patented. [Bailly et al., U.S. Patent Application No. WO2004039468, 2004.] Equilibrium Theory is used (i) to obtain the constraints on the operating parameters and (ii) to identify the operating regimes for the EE-SMB operation. This analysis is performed for a binary mixture whose adsorption behavior is described by a Langmuir isotherm. The operating regimes are translated into regions on the (m 2, m 3) plane representation, which can be easily compared with the corresponding operating regimes of the standard SMB given by the Triangle Theory. In particular, for the EE-SMB operation, the region of complete separation turns out to be a line segment, i.e., a one-dimensional locus. The theoretical findings are confirmed through detailed simulations of the process, and the value of the new EE-SMB operation mode is assessed.