scholarly journals Experimental Study on Aeration Performance and Bubble Characteristics of Inverted Umbrella Aerator

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2809
Author(s):  
Cui Dai ◽  
Jinnan Guo ◽  
Jiawei Liu ◽  
Liang Dong ◽  
Houlin Liu
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Rotational Speed ◽  
High Speed ◽  
Immersion Depth ◽  
Oxygen Mass Transfer ◽  
High Speed Photography ◽  
Aeration Performance ◽  
Bubble Characteristics

In order to understand the aeration performance of inverted umbrella aerator and bubble characteristics in aeration tank under different conditions, and to reveal the internal relationship between bubble characteristics and aeration performance, an experimental bench of dissolved oxygen concentration and high-speed photography was built. Logarithmic oxygen deficit values were fitted under various conditions. The images captured by high-speed photography were processed, then the bubble characteristics were extracted accurately. It was found that the standard oxygen mass transfer coefficient increased linearly with an increase of rotational speed at a certain immersion depth, and increased firstly then decreased with a decrease of immersion depth when rotational speed was kept constant. The bubble size ranged from 0 mm to 1.59 mm under different working conditions, and the variation of the gas holdup was the same as the standard oxygen mass transfer coefficient when the rotational speed and immersion depth were changing. It was shown that bubbles play a leading role in the process of oxygen mass transfer and have a great influence on oxygen mass transfer rate.

Volumetric Oxygen Mass Transfer Coefficient and Surface Tension in Simulated Salt Bioremediation Media

2014 ◽  
Vol 37 (3) ◽  
pp. 519-526 ◽  
Author(s):  
Ellen Cristina Souza ◽  
Dante Augusto Moraes ◽  
Thereza Christina Vessoni-Penna ◽  
Attilio Converti ◽  
Ricardo Pinheiro de Souza Oliveira
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Mass Transfer

Influence of suspended solid particles on gas-liquid mass transfer coefficient in a system stirred by double impellers

2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Anna Kiełbus-Rąpała ◽  
Joanna Karcz
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
High Speed ◽  
Gas Flow ◽  
Research Work ◽  
Experimental Studies ◽  
Solid Particles ◽  
Solid Concentration ◽  
Volumetric Mass Transfer Coefficient

AbstractThe aim of the research work was to investigate the effect of the presence and concentration of solid particles on the gas-liquid volumetric mass transfer coefficient in a mechanically stirred gas-solid-liquid system. Experimental studies were conducted in a tall vessel of the diameter of 0.288 m, equipped with two designs of double stirrers. Three high-speed stirrers were used: A 315, Smith turbine, and Rushton turbine. The following operating parameters were changed: gas flow rate, stirrer speed, and solid concentration. The volumetric mass transfer coefficient was determined using the dynamic gassing-out method. In the range of the measurements conducted, this coefficient was strongly affected by both the presence and the concentration of particles in the system. Generally, a low concentration of particles in the system, equal to 0.5 mass %, caused an increase of the volumetric mass transfer coefficient values for both stirrer configurations compared to a system without solids whilst more particles (2.5 mass %) caused a decrease of this coefficient. It could be supposed that an increase of slurry viscosity affected the decrease of the volumetric mass transfer coefficient at higher solid concentration. An empirical correlation was proposed for volumetric mass transfer coefficient prediction. Its parameters were fitted using experimental data.

Oxygen Mass Transfer Coefficients in a Three-Phase Pulsed Plate Bioreactor

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
K.V. Shetty ◽  
G. Srinikethan
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Immobilized Cells ◽  
Fixed Bed ◽  
Oxygen Mass Transfer ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Three Phase ◽  
Plate Column

Volumetric oxygen mass transfer coefficient is a decisive parameter for the selection of any contactor as an aerobic bioreactor. A pulsed plate column with fixed bed of solids in interplate spaces is a recent innovation in the field of immobilized cell bioreactors. Volumetric oxygen mass transfer coefficients are determined in a three-phase pulsed plate column involving air and water phases and with a fixed bed of glass particles, which can serve as a surface for cell immobilization packed in the interplate spaces. The volumetric mass transfer coefficients obtained in this column range from 0.067 to 0.1495 s-1 in the range of air superficial velocities from 0.011 to 0.047m/s and vibrational velocities from 0.825 to 6cm/s. Volumetric oxygen mass transfer coefficient has increased with the increase in superficial air velocity and vibrational velocity. Empirical correlation relating kLa with these variables was developed. The volumetric oxygen mass transfer coefficient values in the three-phase pulsed plate column are found to be similar or higher than the literature reported values for conventional two-phase pulsed plate columns. The values of volumetric oxygen mass transfer coefficients in the three-phase pulsed plate column are of higher order of magnitude than the literature reported values of volumetric oxygen mass transfer coefficient for many other three-phase gas-liquid-solid reactors. The pulsed plate column with fixed bed of solids is proven to have all the potential to be used as an aerobic bioreactor with immobilized cells due to its better gas-liquid mass transfer characteristics.

Sign in / Sign up

Export Citation Format

Share Document