Packed beds 1126 INDEX

In design practice, a less rigorous parameter, HETP, is used as an index of packing efficiency. Tne HETP is the height of packed bed required to achieve a theoretical stage. The terms Hoe and HETP may be related under certain conditions ... 

A third parameter to consider is the column construction. Thus the sample applicator should provide optimal sample application to give the most performance possible out of the packed bed. Constructions should also allow simple, fast, and reproducible packing of the column. Because costs for repacking of columns are a substantial operating cost item in industrial chromatography, the selection of column construction from this point of view is also important. Some novel column constructions allow very simple procedures both for laboratory and for industrial scale (e.g., INdEX columns, see Section V). 

The separation impedance is a measure of column performance and allows one to compare, for example, capillary columns to packed beds. The performance index is a measure of the quality of the separation and contains a strong dependence on analysis time. 1 would prefer a criterion that preserves the... 

As demonstrated in Figure 11.12, the trade-off index of microstructured channels is roughly five times higher compared to that of packed beds. This means that the energy dissipation for the same mass transfer performance in a packed bed is five times higher than in a microchannel. 

The performance of the foam can be evaluated based on the trade-off index defined in Eq. (11.35). In Figure 11.12, the index of foams is compared to microchannels and packed beds. Depending on the Re number, the performance approaches the performance predicted for microchannels and monoliths. Therefore, open cell foams must be considered as valuable catalyst supports for efficient PL... 

Principle A glass column is packed with silica particles. A mobile phase is prepared that has the same refractive index as the silica particles. The migration of a dye through the invisible bed is observed. Defects in the bed are easily observed. 

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