(444g) Equilibrium Theory Based Design of Simulated Moving Bed Processes Under Reduced Purity Requirements. Linear Isotherms

SMB schemes operated under reduced purity requirements can be interesting where complete separation of the binary feed mixture is not essential. Such requirements, which are likely to grow in the coming years, exist in the agrochemical industries, where only an enantiomerically enriched product is often required. This is also useful for hybrid separations such as the SMB-crystallization process where a partial enrichment of the products is performed by the SMB. The design of simulated moving bed processes under reduced purity requirements for systems whose isotherm is linear is considered. Based on the equilibrium theory of chromatography, explicit equations to uniquely identify the separation region that will ensure specified extract and raffinate purities are derived. In the frame of the "triangle theory?, this results in a pentagonal region in the (m2, m3) plane, operating within which will ensure an extract and raffinate purity better than the specified one. The identification of the vertices of this region requires only the knowledge of Henry constants of the solutes, the concentration of the solutes in the feed and the purity specifications. The derivation of the design equations is illustrated and these results are validated using numerical simulations.