scholarly journals Effect of Contaminants on the Gas Holdup and Mixing in Internal Airlift Reactors Equipped with Microbubble Generator

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Surya K. Pallapothu ◽  
Adel M. Al Taweel
Keyword(s):  
Sodium Dodecyl ◽  
Pilot Scale ◽  
Gas Holdup ◽  
Superficial Velocity ◽  
Hydrodynamic Performance ◽  
Two Phase ◽  
Liquid Circulation ◽  
Circulation Velocity ◽  
The Impact ◽  
Airlift Reactors

The impact of contaminants on the gas holdup and mixing characteristics encountered in internal airlift reactors was investigated using a 200 L pilot scale unit equipped with a two-phase transonic sparger capable of generating microbubbles. Small dosages of a cationic surfactant (0–50 ppm of sodium dodecyl sulfonate (SDS)) were used to simulate the coalescence-retarding effect encountered in most industrial streams and resulted in the formation of bubbles that varied in size between 280 and 1,900 μm. Gas holdups as high as 0.14 were achieved in the riser under homogeneous flow regime when slowly coalescent systems were aerated at the relatively low superficial velocity of 0.02 ms−1, whereas liquid circulation velocities as high as 1.3 ms−1were achieved in conjunction with rapidly coalescent systems at the same superficial velocity. This excellent hydrodynamic performance represents a 5-fold improvement in the riser gas holdup and up to 8-fold enhancement in the liquid circulation velocity and is expected to yield good mixing and mass transfer performance at low energy dissipation rates.

Hydrodynamic Flow Regimes, Gas Holdup, and Liquid Circulation in Airlift Reactors

1998 ◽  
Vol 37 (4) ◽  
pp. 1251-1259 ◽  
Author(s):  
Mohamed E. Abashar ◽  
Udi Narsingh ◽  
Andre E. Rouillard ◽  
Robin Judd
Keyword(s):  
Flow Regimes ◽  
Gas Holdup ◽  
Hydrodynamic Flow ◽  
Liquid Circulation ◽  
Airlift Reactors

scholarly journals Effect of Superficial Gas Velocity on Continuous Hydrogen Production by Anabaena sp. in an Internal-loop Airlift Bioreactor

2021 ◽  
Author(s):  
Zahra Zarei ◽  
Peyman Malekshahi ◽  
Mohammad Hossein Morowvat ◽  
Rahbar Rahimi ◽  
Seyyed Vahid Niknezhad
Keyword(s):  
Mass Transfer ◽  
Hydrogen Production ◽  
Light Intensity ◽  
Gas Flow ◽  
Biomass Concentration ◽  
Gas Holdup ◽  
Liquid Circulation ◽  
Airlift Photobioreactor ◽  
Circulation Velocity ◽  
Liquid Circulation Velocity

Abstract Global warming and rising air pollution which has been caused by using too much fossil fuel has led to look for a new clean source, sustainable and eco-friendly of energy like H2, which can be produced by cyanobacteria and microalgae. In this study, Anabaena sp. was used in a continuous operation to achieve biohydrogen production. To this end, an airlift photobioreactor (20 L) was considered. The effects of the gas holdup, liquid circulation velocity, and the amount of dissolved oxygen on hydrogen production were investigated. Gas holdup, liquid circulation velocity, and KLa (mass transfer coefficient) showed an upward trend by increasing the velocity of the inlet gas. Maximum biomass concentration of and maximal H2 production were observed 1.2 g L-1 d-1 and 371 mL h-1 PBR-1, respectively under light intensity of 3500 lux/m2 applying a light-dark cycle in 7 days, at Ad/Ar of 1.25 and 0.185 and 0.542 cm/s. pH, temperature (30+2 °C), light intensity, and inlet gas flow to the bioreactor (containing 98% air and 2% carbon dioxide) were remained steady. Using the airlift photobioreactor with a good mass transfer and light availability to cyanobacteria growth can be a cost-effective and environmentally technology for biological H2 production.

scholarly journals Hydrodynamics of an airlift reactor for aeration in molten sulfur

2021 ◽  
Author(s):  
Junjie Wang ◽  
Xiao Xu ◽  
Qiang Yang ◽  
Wei Wang ◽  
Yudong Li ◽  
...  
Keyword(s):  
Bubble Diameter ◽  
Gas Holdup ◽  
Airlift Reactor ◽  
Gas Velocity ◽  
Liquid Circulation ◽  
Molten Sulfur ◽  
Circulation Velocity ◽  
Liquid Circulation Velocity ◽  
Superficial Gas Velocity ◽  
Reactor Height

An industrial-scale internal loop airlift reactor is used to remove volatile gas from high-viscosity molten sulfur. The effects of the superficial gas velocity and reactor height on the hydrodynamic characteristics were studied. The gas holdup, average bubble diameter, and liquid circulation velocity in the reactor under different conditions were analyzed using computational fluid dynamics simulation. The superficial gas velocity was varied from 0.0056 m/s to 0.05 m/s at a constant reactor height of 15 m. The total reactor height was varied from 5 m to 25 m at a superficial gas velocity of 0.0389 m/s.Based on the correlation between the gas holdup and liquid circulation velocity proposed by Chisti (1988), an optimized correlation between the gas holdup and liquid circulation velocity was developed by considering the influence of the bubble diameter. The results obtained using the proposed correlation were compared with those obtained using the Chisti correlation and simulation.

scholarly journals Effects of air-lift reactor dimensions on its hydrodinamic characteristics

2010 ◽  
Vol 64 (1) ◽  
pp. 35-46
Author(s):  
Milan Milivojevic ◽  
Danijela Andrejic ◽  
Branko Bugarski
Keyword(s):  
Liquid Velocity ◽  
Solid Particles ◽  
Hydrodynamic Characteristics ◽  
Solid Loading ◽  
Phase System ◽  
Two Phase ◽  
Liquid Circulation ◽  
Airlift Bioreactors ◽  
Circulation Velocity ◽  
Liquid Circulation Velocity

In this study the hydrodynamic characteristics of the external loop airlift bioreactors were investigated. The influence of reactor height and solid particles concentration on the mean liquid circulation velocity was examined. Also, the possibility of theoretical prediction of this liquid circulation velocity was assessed. The correlation originally proposed by Glennon et al. (Chem. Eng. Commun. 121 (1993) 183-192) for two phase system liquid velocity prediction was extended and corrected for application to three phase systems. The accuracy of this new correlation was tested on our experimental data. The corrected correlation shows higher accuracy than the originally proposed one. In addition, the influence of reactor geometry and solid loading on reactor working performances was established.

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