Empirical models for the hydrodynamics of turbulent bed contactor with non-Newtonian liquids: (part 3)

Abstract

Turbulent bed contactors (TBC) are three-phase fluidized beds which form an important class of process equipment used in many applications. In this work, experiments were conducted to investigate bed expansion and gas holdup behavior in TBC with non-Newtonian fluid for which limited information is reported in the literature. Aqueous solutions of carboxymethyl cellulose (CMC) with apparent viscosities ranging from 5 to 25 mPa.s were sprayed over beads packing at the top of the column. Forced airflow entered the bottom of the column to fluidize hollow plastic beads. The effect of rheological properties of CMC aqueous solutions on bed expansion and gas holdup was investigated upon variations of operating conditions. Two regions of bed expansion were existing when liquid flow rates were lower than 5.05 × 10−4 m3/s. Gas holdup decreased drastically for more viscous liquid solutions. Empirical models were developed for important hydrodynamic parameters of TBC such as pressure drop, liquid holdup, minimum fluidization velocity, and bed expansion as a function of several operational variables. Different dimensionless groups were formed from the available set of variables and empirical models were proposed and fitted based on maximum R2 criteria. The models developed can be used in the design and optimal operation of TBC.

Keywords: Bed expansion, Empirical models, Gas holdup, Non-Newtonian liquids