Investigations of Performance Characteristics Including Limitations Due to Flow Instabilities in Continuous SPLITT Fractionation

Abstract

An investigation of SPLITT fractionation is conducted to improve its overall performance. Particular attention is devoted to factors which degrade separation resolution in the thin SPLITT channels, including the development of instabilities due to unstable stratification of density. The presence of these instabilities is quantified using the Richardson number (Ri) and the flow-rate ratio [Vdot] (a)/[Vdot] (a′), where [Vdot](a) and [Vdot] (a′) are volumetric flow rates at the top outlet substream and the top inlet feed substream, respectively. The stability boundary separating the stable and unstable flow domains is identified in terms of these parameters. Based on these criteria, the region most suitable for operation of SPLITT fractionation corresponds to [Vdot] (a)/[Vdot] (a′) ≥ 8, and Ri in the range of 0.001 to 0.0055, depending upon the value of [Vdot] (a)/[Vdot] (a′) Experimental verification is provided by the successful separation of a sample of glass bead particles using a multistage fractionation system.

Key Words:

• SPLITT fractionation
• Flow instability
• Density stratification
• Richardson number

Additional information

Notes on contributors

J. C. Giddings

Distinguished Professor Cal Giddings passed away on October 24, 1996. We greatly miss our friend, colleague, and mentor.