Preliminary Assessments of Combined Effects of Surface Tension and Viscosity on Bubble Column Hydrodynamics

Abstract

The present contribute reports results of combined effects of liquid features on the hydrodynamics of a lab-scale bubble column. In particular, the combined effects of viscosity - Newtonian fluid – and surface tension were investigated. The experimental apparatus consisted of a 10 L bubble column: a 120 mm ID,1.8 m high Plexiglas column equipped with 0.4 mm needles gas distributor, free area 0.13%. The unit was equipped with gas flow controller, humidifier, diagnostic instrumentation, and data acquisition unit. The unit was operated batchwise with respect to the liquid phase at temperature of 25°C. The liquids investigated were aqueous solutions of sodium alginate and sodium chloride. The concentration of sodium alginate was increased up to 0.5%W, the sodium chloride up to 2 M. Solutions were characterized in terms of viscosity, surface tension, and conductivity. The viscosity ranged between 0.90 and 20 mPa•s, the surface tension between 68.4 and 71.9 mN/m, and conductivity between 0 and 5.34 S/m. Results showed that the transition velocities between hydrodynamic regimes (homogenous regime – transition regime – heterogeneous/turbulent regime) strongly depends on investigated liquid features.