Optimization of simulated moving bed and Varicol processes

Continuous chromatographic processes with a small number of columns: Comparison of simulated moving bed with Varicol, PowerFeed, and ModiCon

“…1(b), where χ is constant for SMB but variable for Varicol. In such a way, more degrees of freedom are added to the classical SMB process, making it possible to achieve better performance [Zhang et al, 2002[Zhang et al, , 2003aToumi et al, 2003;Pais and Rodrigues, 2003].…”

“…In fact, there is a clear trend in applications to operate SMB with 5 or 6 columns, instead of 8, which was previously regarded as the minimum number of columns for SMB units. The second approach aims at improving the unit's separation efficiency either by optimizing the adsorptivity of the solutes in the different sections of the unit, such as in supercritical fluid SMB [Nicoud and Perrut, 1992;Mazzotti et al, 1997b;Di Giovanni et al, 2001;Denet et al, 2001], temperature gradient SMB [Migliorini et al, 2001] and solvent gradient SMB [Jensen et al, 2000;Antos and Seidel-Morgenstern, 2001;Abel et al, 2002;Houwing et al, 2003], or more recently by operating SMB under more complex dynamic conditions, as it is the case in the Varicol Zhang et al, 2002Zhang et al, , 2003aToumi et al, 2003;Pais and Rodrigues, 2003], PowerFeed [Kearney and Hieb, 1992;Kloppenburg and Gilles, 1999;Zang and Wankat, 2002a, b;Zhang et al, 2003bZhang et al, , 2004 and ModiCon [Schramn et al, 2002[Schramn et al, , 2003 processes. These new operation modes do not keep constant conditions during one switching period t * , as in a standard SMB, but allow for variation of the column configuration, the fluid flowrates, or the feed concentration, respectively.…”

Modeling for Taxol® Separation in a simulated moving bed

“…A fast and accurate resolution scheme, using a closed-form solution, was proposed by Dünnebier et al (1998). However, when a general rate model is used to represent the mass transfer in each column, almost all authors use the orthogonal collocation technique to solve the problem (Ching et al, 1991;Mallmann et al, 1998;Toumi et al, 2003;Yu and Ching, 2003). The aim of this work was to develop an alternative numerical resolution strategy for the dynamic prevision of linear adsorption processes in a multicomponent SMB system, using a general rate model.…”

Simulation assessment of continuous simulating moving bed chromatography process with partial feed and new strategy with partial feed

“…Further modifications of the simulating moving bed techniques are: the PowerFeed SMB process (Kearney and Hieb, 1992;Kloppenburg and Gills, 1999;Zhang et al, 2003aZhang et al, , 2004a in which the flow rates in the unit are allowed to change during a column switching time following a predefined pattern; in Varicol (Adam et al, 2000, Hombourger et al, 2000Zhang et al, 2002Zhang et al, , 2003bToumi et al, 2003;Pais and Rodrigues, 2003) the basic principle of the process consists of an asynchronous shift of the inlet/outlet lines in a system of multicolumns in a recycle loop; in ModiCon (Schramn et al, 2002(Schramn et al, , 2003, another modification of classical SMB, the flow rate and the column configuration are kept unchanged while modulating the feed concentration during the switching period of the SMB process. Schematic representations of these three processes, i.e., PowerFeed, Varicol and ModiCon, in comparison to the basic SMB system, are shown in Figure 1.…”