York Alexander Beste

Optimization of simulated moving bed plants with low efficient stationary phases: separation of fructose and glucose

An optimization procedure for simulated moving bed (SMB) plants with low efficient stationary phases is presented. The new aspect is that the desorbent consumption can be cut by 70% by running the plant with lower internal liquid flows and a corresponding larger switch time while the productivity is kept constant. This concept was validated by the separation of fructose and glucose in water on a calcium resin with an eight-column SMB plant. The separation can be predicted well by a true moving bed (TMB) and a simulated moving bed simulation. Adsorption isotherms were determined up to 300 kg/m3 for glucose and 500 kg/m3 for fructose from 25 to 80 degrees C. Experimental SMB runs were performed over a wide range of feed concentrations (10-350 kg/m3) and temperatures (25-80 degrees C). The strong influence of the delay volume is pointed out. For an experimental run with high feed concentration a complete set of data is presented. To reduce biological growth separation at 80 degrees C is recommended.

Side-stream simulated moving-bed chromatography for multicomponent separation

Simulated countercurrent moving-bed chromatography is a thermal separation process which due to its high selectivity, is often used to separate very similar molecules. As with a rectification column, a conventional chromatographic separator unit is designed with two product outlets for each component of the binary mixture. However, since multicomponent mixtures are more likely to be encountered in reality, this work extends distillations use of side-stream withdrawal to moving-bed chromatography in order to investigate the suitability of a side-stream SMB for separating multicomponent systems.

CFD simulation tool for the systematic examination of effects on band spreading in large radial columns

Especially the scale up of analytical chromatographic columns for preparative purposes in combination with complex separation conditions leads to non-trivial problems. CFD-Simulation together with basic experiments is an efficient tool to clear up and to optimise the multiple coherent processes in fixed bed columns. For detailed examinations of the inner column effects a three dimensional model for a fixed bed chromatographic column was developed by using the commercial CFD software package FLUENT™. Based on the results of the CFD-Simulation we want to present the interdependence between the column diameter and the height of a theoretical plate [HETP]. Furthermore we will specify the effect of the inlet and outlet distributors (frits) on the HETP. In our simulations we could show the possibility to optimize the separation performance of the column by subcooling the feed below the temperature of the column wall.