(102a) Determination of Drop Size Distribution In a Centrifugal Contactor

O'Hern, T. J., Sandia National Laboratories
Shelden, B., Sandia National Laboratories

Centrifugal contactors are widely used in separation and mass transfer applications involving immiscible phases.  Quantifying drop size distributions in such processes is critical to understanding and tuning mass transfer characteristics between immiscible phases.  Many studies have focused on the complex flows in both the annular and separation regions of the contactor.  However, the magnitude and distribution of droplet sizes in the mixing region has not been characterized.  For mass transfer applications, drop size and, thus, surface area are key factors.  Through the use of high speed imaging, we measure drop size distributions in the annular mixing region for mixtures of silicone oil and water.  We measure the evolution of the drop size distribution as the material travels from the mixing region to the vane region.  Further, we quantify size distributions for air bubbles that are entrained in the flow.  The distributions are examined over a range of rotor speeds from 1100 to 2100 rpm for silicone oil viscosities from 5 to 20 cSt.  Drop sizes for both air and oil (dispersed phase) are found to be normally distributed at locations near the surface of the mixing zone.  Near the bottom of the mixing zone, the distributions become log-normal and the mean drop diameter shifts to lower values.

Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.