RESOLUTION DETERIORATION AND OPTIMAL OPERATING-CONDITIONS IN CENTRIFUGAL SPLITT FRACTIONATION .1. STABLE DENSITY GRADIENTS

In this study, factors which deteriorate resolution in thin centrifuga l SPLITT channels with stable density gradients are examined. The effe cts of channel rotation, channel flow velocity, and channel flow rate ratios on resolution are examined experimentally. Results indicate tha t the stability boundary which separates the regions of good and bad s eparation (or the regions where channel flow is stable and unstable) c orresponds to a Reynolds number (Re) of 13.5. For Re > 13.5, separatio n resolution is poor and the fractional deviation between theoretical and experimental retrieval is higher than 10%. This is the result of f low instabilities induced by Coriolis and inertial forces in the chann el that cause unwanted mixing of feed and carrier substreams. This res ult establishes limits on maximum channel flow rates and thus offers g uidelines for the design of new channels. In comparison to the instabi lities induced by channel rotation and channel velocity, the effect of the flow rate ratio (V) over dot(b')/(V) over dot(a') on resolution i s less significant for the range of flow rate ratios examined. (C) 199 7 John Wiley & Sons, Inc.