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Abstract:
The continuous simulated moving bed technology is increasingly applied for the production of value-added products. It offers the advantages of high throughput and low solvent consumption. However, the conventional SMB-technology is only suitable for the separation of binary mixtures. For the isolation of a certain target component out of multi-component mixture, it is typically necessary to apply conventional batch chromatography. A disadvantage of batch chromatography is the limited productivity due to low loading factors. In the contribution a combination of batch chromatography and subsequent continuous countercurrent chromatography is investigated theoretically. The procedure considered can be divided into two steps. At first, the sample is injected on a batch column. Applying appropriate collecting strategies, fractions can be taken in which the target component is located in the first or last position of the elution order. Subsequently, the fractions obtained using batch chromatography are fed to a continuous countercurrent unit for isolating the target component in one of the two effluent streams. Using this concept it is not necessary to obtain the pure target component already in the first step. Thus, higher loading factors are permitted for batch chromatography. The separation process in the batch column is quantified using conventional models such as the equilibrium dispersive model. For the ease of discussion, ideal and linear case is considered in the simulation of continuous countercurrent chromatography. The analysis and the design of the combined process is discussed by investigating the separation of an intermediate component from a ternary mixture. Concepts to determine optimal operating points and to maximize the productivity are presented. It is shown that the combined technique has the potential to offer several advantages compared to batch chromatography alone. The important impact of the parameters of the adsorption isotherms on the performance of the combined process is demonstrated based on the results of parametric calculations.
