The influence of liquid physical properties on entrainment inside a sieve tray column

Abstract

Entrainment data were measured with Isopar G, n-butanol, silicone oil, water and ethylene glycol in a rectangular sieve tray column to cover relatively large ranges of liquid density (739–1095kg/m3), surface tension (19.9–60mN/m) and dynamic viscosity (0.9–48.8mPas). CO2 was used as the gas phase. Liquid flow rates ranged between 2.8 and 80m3/(hm), with gas flow factors (Fs) between 1.9 and 3.9m/s(kg/m3)0.5. The results showed a complex interaction of liquid physical properties influencing entrainment. An increased surface tension and higher liquid density resulted in fewer, but larger diameter, heavier droplets that decreased entrainment. Liquid viscosity and its combination with surface tension were shown to have a non-monotonic effect on entrainment. Liquids with relatively low viscosity and low surface tension formed higher dispersion layers with many small projected droplets, thus increasing entrainment. However, an increase in liquid viscosity beyond a critical point caused a decrease in entrainment. In general, notable deviations were observed between existing, published entrainment prediction correlations and the data generated in this study. This is most probably due to the fact that such correlations had been developed with limited liquid property variations, not covering the full spectrum of this study.