Mass-Transfer Behaviors in Alcohol Solutions in an Internal-Loop Airlift Reactor of 5-m Height

Abstract

Gas–liquid mass-transfer behaviors in aqueous alcohol solutions were studied in an internal-loop airlift reactor of 5-m height and 0.28-m i.d. in the superficial gas velocity (U g) range from 2.0 to 10.0 cm/s. Air and aqueous n-butanol solutions were used as the gas and liquid phases, respectively. It was found that the volumetric mass-transfer coefficient decreased with increasing n-butanol concentration (C A) below a critical C A value of 0.5 wt % and increased with increasing C A above this concentration. To confirm this result, further experiments were also carried out in a bubble column of 0.12-m i.d. at U g = 6 cm/s, and similar results were obtained. Further analysis showed that the value of k l a/αg was independent of the superficial gas velocity and equal to 0.21 1/s in the air–water system; however, it decreased with increasing C A up to 0.25 wt % in n-butanol solutions, and further addition of n-butanol had no effect on k l a/αg. A critical C A value of 0.5 wt % was also found for the liquid-side mass-transfer coefficient (k l). Below this concentration, k l decreased with increasing C A, whereas above this concentration, further addition of n-butanol had no effect on k l.

Efficient Control of Microbubble Properties by Alcohol Shear Flows in Ceramic Membrane Channels

“…It is known that alcohols are coalescence‐hindering . An alcohol molecule has a hydrophilic part (hydroxyl group) and a hydrophobic part (carbon chain).…”

Volumetric gas-liquid mass transfer coefficient in an external-loop airlift reactor with inserted membrane

“…Furthermore, alcohols can be used to induce a behavior simi-lar to the fermentation media in aerobic bioprocesses [10]. Addition of alcohols has a two-fold effect on k L a [11]. The presence of an alcohol tends to increase a due to a decrease in bubble diameter and increase of the gas holdup.…”

“…Several researchers [5,[12][13][14] using an ELAR reported that the k L a values increased with increasing alcohol concentration in solutions, while Al-Masry and Dukkan [15] reported an opposite trend. Deng [11] has observed that the k L a values had the minimum in n-butanol solution at concentration of 0.5 wt%. Hence, there is a relative lack of data in open literature and more detailed data are needed to provide better understanding of the mass transfer mechanism in the presence of alcohol.…”

Effect of Surface Tension on Hydrodynamics and Mass Transfer Coefficient in Airlift Reactors

“…In an airlift reactor, the mass transfer coefficient depends on gas‐phase holdup, flow regime transition, bubble size distribution, bubble coalescence and breakup, liquid‐side mass transfer coefficient, and interfacial area , . Albijanic et al.…”

“…Airlift reactors are multiphase contractors widely used in chemical, petrochemical, and biochemical industries due to advantageous characteristics in terms of high heat and mass transfer, low shear, perfect mixing, easy scale‐up, and low cost . Riser, downcomer, gas‐liquid phase separator and sparger are the main parts of airlift reactors.…”