Gas holdup is one of the most important hydrodynamic parameters needed for reliable design, performance estimation, and scale-up of stirred tank reactors (STRs). In the present work, local gas holdup is measured in an acrylic stirred tank reactor equipped with a Rushton impeller using X-ray computed tomography (CT) for many different operating conditions. Power consumption for different operati...

A 4-m high, 15.24-cm diameter semi-batch bubble column connected to one of three perforated plate gas distributors with open area ratios A = 0.57%, 0.99%, and 2.14% is employed to study gas holdup and flow regime in Rayon and Nylon fiber suspensions. This study determines the effect of superficial gas velocity, fiber type, fiber mass fraction, fiber length, and aeration plate open area ratio on...

In this paper, we present an experimental study on mass transfer of oxygen into water in an oscillatory baffled column (OBC). The objective of this work is to establish the contribution of individual parameters, such as the size of bubbles and the gas holdup, to the overall volumetric mass transfer coefficient (kLa). Our results show that the gas holdup is the most important factor. The liquid-...

Lu Han and Muthanna H. Al-Dahhan A gaseous tracer technique and procedures were developed and implemented to measure the axial dispersion of gas phase in a slurry bubble column reactor using air-water-glass beads (100ìm). Residence time distribution curves were obtained by measuring the response of gaseous tracer pulse input. The gas phase axial dispersion coefficient, Dg, was determined from m...

The gas holdup and flow dynamics in a laboratory scale Rushton-turbine flotation tank were simulated using the dispersed k- turbulence model and Eulerian-Eulerian multiphase modelling approach. The inherent uncertainties in the CFD predictions were quantified by examining the model and numerical (i.e., discretization) uncertainties. The contribution of model uncertainty was explored by conside...

Gas holdup and bubble size are important parameters for simulation and designing in bubble column reactors. Because based on these parameters, the available gas-liquid interfacial area is defined for mass transfer. In this paper, the results of applying magnetic fields on the velocity field and volume fraction of gas holdup are reported. Hydrodynamics of the bubble column in the reactors is inv...

In the present study, the influence of superficial gas velocity and fluid properties on gas holdup and liquid circulation velocity in a three-phase external loop airlift column using polystyrene (0.0036 m diameter and 1025.55 kg/m density) and nylon-6 (0.0035 m diameter and 1084.24 kg/m density) particles with aqueous solutions of alcohols (isoamyl alcohol and propanol) as liquids were investig...

An external liquid circulation is introduced into a traditional internal loop reactor in order to improve liquid circulation and increase the interface between gas and liquid phases. The effects of superficial gas velocity and external liquid circulation velocity on local and overall gas holdups are explored experimentally and numerically in the loop section of a combined gas-liquid contactor, ...

The gas holdup behavior in a nylon fiber suspension with various fiber lengths (L = 2, 3, and 6 mm) is investigated. Experiments are performed over a range of superficial gas velocities (Ug≤ 18 cm/s) and a range of fiber mass fractions (0 ≤ C ≤ 1.8%) in a 15.24-cm-diameter semibatch bubble column. Day-to-day variations in the gas holdup create difficulties in interpreting the effect of the fibe...

the main objective of this paper is to examine the effect of nanomaterials on mass transfer coefficient in bubble type absorption of carbon dioxide by experiment. the absorption process is carried out in a bubble column and in room temperature. mass transfer coefficient, saturated concentration of co2, and gas holdup are determined in this system. the kinds of nanomaterials, the concentrations ...