Drop size and holdup in a reciprocating plate extraction column

This paper reports measurements of droplet sizes and holdup in liquid—liquid systems in a 2 in. dia. reciprocating plate extraction column, in the absence of mass transfer.The Sauter mean droplet diameter was found to depend on the product of plate amplitude and frequency and on the system properties, but it was not in general affected by the throughput. It could be correlated fairly well using a turbulent dispersion model similar to that which has been applied successfully to dispersions in stirred tanks.A simple hydrodynamic model is proposed for the holdup, assuming the droplet diameter to depend on turbulent energy dissipation. This model is consistent with the experimental data if it is assumed that droplets in kerosene undergo hindered circulation while droplets in methyl isobutyl ketone circulate freely. The model also agrees with some previously published data on holdup in a gas—liquid system in a pulsed column, assuming that the gas bubbles circulate freely.