Effect of a gas–liquid separator on the hydrodynamics and circulation flow regimes in internal‐loop airlift reactors

Abstract

The role of the gas±liquid separator on hydrodynamic characteristics in an internal-loop airlift reactor (ALR) was investigated. Both gas holdup and liquid velocity were measured in a 30 dm 3 airlift reactor with two different head con®gurations: with and without an enlarged separator. A magnetic tracer method using a neutrally buoyant magnetic particle as¯owfollower was used to measure the liquid velocity in all sections of the internal-loop airlift reactor. Average liquid circulation velocities in the main parts of the ALR were compared for both reactor con®gurations. At low air¯ow rates the separator had no in¯uence on gas holdup, circulation velocity and intensity of turbulence in the downcomer and separator. At higher super®cial air velocities, however, the separator design had a decisive effect on the hydrodynamic parameters in the downcomer and the separator. On the other hand, the gas holdup in the riser was only slightly in¯uenced by the separator con®guration in the whole range of air¯ow. Circulation¯ow regimes, characterising the behaviour of bubbles in the downcomer, were identi®ed and the effect of the separator on these regimes was assessed. # 2001 Society of Chemical Industry Keywords: airlift reactor; separator; circulation regimes; circulation velocity;¯owfollower

Multiphase flow characteristics of a novel internal-loop airlift reactor

“…The gas-liquid separator at the top of the reactor has important influence on the performance of the ALRs [5,6]. This influence is a combination of its ability to separate gas from the liquid or liquid-solid phase and its hydraulic resistance.…”

CFD analysis of flow regimes in airlift reactor using Eulerian‐Lagrangian approach

“…Comparison of predicted gas holdup profiles with experimental data of Klein et al: (a) average gas holdup in the riser, (b) average gas holdup in the downcomer.…”

Bioreactors: Airlift Reactors

“…The gas separator is often overlooked in descriptions of experimental ALR devices, although it has considerable influence on the fluid dynamics of the reactors. The geometric design of the gas separator will determine the extent of disengagement of the bubbles entering from the riser (17,59,60). In the case of complete disengagement, clear liquid will be the only phase entering the downcomer.…”