(401b) Effects of Physical Properties and Phase Dispersion on Sieve Tray Extractor Performance

Authors: 
Seibert, F., University of Texas at Austin
De Villiers, W. E., Shell Global Solutions (US) Inc.
Bravo, J., Consultant
Sieve trays are very often used in commercial-scale liquid extraction applications in the chemical and petrochemical industries because of their reliable scale-up, absence of moving parts and ability to handle high throughputs. Properly designed sieve trays eliminate backmixing and provide for the reformation of drops. The hydraulic and mass transfer characteristics depend on many parameters such as the tray geometry, physical properties and which phase is dispersed. In particular, liquid viscosity and interfacial tension can have a significant effect on mass transfer and drop coalescence. Published sieve tray extraction data are quite limited regarding the variation of interfacial tension, solvent viscosity and density. The overwhelming majority of available data involve an aqueous phase and a hydrocarbon phase with very little information published on two immiscible hydrocarbon phases.

The paper expands the publically available database on sieve tray extraction performance with the study of the sulfolane/n-heptane test system. Toluene was chosen as the transferring solute. In this study, following effects were studied:

  • flow velocities
  • addition of transferring solute
  • mass transfer direction
  • which phase is dispersed
  • coalescer material of construction
  • density difference, interfacial tension and sulfolane viscosity

In this work, the hydraulic and mass transfer results are compared with the SRP predictive models for sieve tray extraction design.