A tomographic study on the effect of liquid/slurry viscosity in a slurry bubble column

Slurry bubble column (SBC) reactors find a wide range of application in the chemical process, pharmaceutical and biochemical industries, etc. Over the past decades, various experimental and numerical studies have been done in an attempt to capture the impact of solids in terms of solid concentration and solid particle size on various hydrodynamic propertices1-4. However, still the knowledge about the possible effects of solids on the gas-liquid system is not understood clearly. Due to this lack of clear understanding on the influence of the solid particles, the prediction of the complex flow behavior of gas-liquid-solid flows in slurry bubble column reactor becomes very difficult. In most of numerical investigations5-6, the gas flow behaviour was predicted considering the uniform suspension of the solids in the liquid phase, i.e. the slurry phase was modeled as a single pseudo-homogeneous phase. The assumption of a pseudo-slurry phase may probably be reasonable for smaller particles where particle Reynolds number, ReP, is below 0.3 and stokes law assumption is valid. However, for larger particles, where ReP is higher than 0.3, the effect of the solid phase on the liquid cannot be neglected. Furthermore, all the available correlations for slurry viscosity7-8 consider only the effect of Cs, neglecting the effect of particle size and superficial gas velocity. In the present work, an attempt has been made to study the effect of viscosity in two-phase (air / water + glycerol) system and compared with the apparent (slurry) mixture viscosity in three-phase (air / water +glass particles) system on the hydrodynamic parameters like gas holdup at approximately same viscosities under similar operation conditions.