Bubble and Heat Transfer Phenomena in Viscous Slurry Bubble Column

Abstract

Heat transfer and bubble phenomena were investigated by adopting the drift flux model in a viscous slurry bubble column reactor (SBCR), having a diameter of 0.0508 m (ID) and height 1.5 m. The effects of superficial gas velocity (0.002 - 0.164 m/s), solid concentration (0 - 20 wt%) and liquid viscosity (paraffin oil; 16.9 mPa∙s and squalane; 25.9 mPa∙s) on the gas holdup and heat transfer characteristics were examined. It was observed that the gas holdup increased with increasing superficial gas velocity (UG), but decreased with increasing solid concentration (SC) or slurry viscosity. The degree of non-uniformity in a SBCR could be determined by the modified drift flux model at the heterogeneous flow regime. The local heat transfer coefficient (h) between the immersed heater and the bed decreased with increasing liquid viscosity and SC, but it increased with increasing UG. The modified Nusselt number including the gas holdup and local heat transfer coefficient was well correlated in terms of dimensionless groups such as Reynolds and Prandtl numbers.