Abstract
Gas-liquid dispersion characteristics were experimentally investigated by measuring largest Lyapunov exponent (LLE), relative power demand (RPD), and local gas holdup in a stirred tank with rigid impellers, rigid-flexible impellers, and punched rigid-flexible impellers. Results showed that punched rigid-flexible impeller could enhance the value of LLE, namely, the chaotic mixing degree of gas-liquid system compared with rigid impeller and rigid-flexible impeller. RPD for punched rigid-flexible impeller was higher than that for rigid impeller and rigid-flexible impeller. The local gas holdup of punched rigid-flexible impeller system was higher than those of rigid impeller system and rigid-flexible impeller system at the same Pg,m. In addition, a long flexible connection piece length could improve the chaotic mixing degree, RPD, and local gas holdup. The aperture diameter of 8 mm and free area ratio of 12 % of punched rigid-flexible impeller were particularly suitable for the gas-liquid dispersion process in this work.
Acknowledgements
The study was supported by the National Natural Science Foundation of China (21576033, 21636004), National key research and development project (2017YFB0603105), National Sci-Tech Support Plan (2015BAB17B01), Chongqing Special Social Undertakings and People's Livelihood Security Science and Technology Innovation (cstc2015shmszx100024), and Central University of Basic Scientific Research Special Project (106112017CDJQJ228808).
Nomenclature
- H
liquid height, m
- H0
impeller spacing, m
- Z
axial distance, m
- T
stirred tank diameter, m
- D
impeller diameter, m
- L1
blade length of rigid impeller, m
- L2
rigid blade length of rigid-flexible impeller/punched rigid-flexible impeller, m
- L3
flexible connection piece length of rigid-flexible impeller/punched rigid-flexible impeller, m
- LLE
largest Lyapunov exponent
- m
embedded figure
- τ
delay time, s
- X1, X2, …, XK, …, XN
time series
- Y(t0)
initial point
- Y0(t0)
nearest neighbor point
- L0
distance between the initial point and the nearest neighbor point
- ε
fixed value >0
- Q
end point of the time series
- M
total iterative number of the tracking evolution process
- ti
tracking time, s
- ε
local gas holdup
- t1i
ith (i = 1, 2, … ) bubble passage time in sensor 1, s
- t2i
ith (i = 1, 2, … ) bubble passage time in sensor 2, s
- Fr
Froude number, N2D/g
- Vs
gas velocity, m·s-1
- Pg,m
power consumption per unit mass, W·kg-1
- P0
ungassed power consumption, W
- Pg
gassed power consumption, W
- Np
ungassed power number
- Npg
gassed power number
- N
impeller rotational speed, s-1
- Flg
gas flow number, Qg/ND3
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Articles in the same Issue
- review
- Application of Microfluidics in Process Intensification
- article
- A Versatile Converter of Liquid Hydrocarbons for the Production of Reducing and Carbonization Atmospheres
- Design of Impeller Blades for Intensification of Gas-Liquid Dispersion Process in a Stirred Tank
- Experimental Study of the Mixing and Segregation Behavior in Binary Particle Fluidized Bed with Wide Size Distributions
- Studies of Dehydrogenation Reaction over Zinc-Alumina Catalyst
- Pressure-Leaching Behavior of Nickel from Ni–Mo Ore in Aqueous Oxygenated Media
- Impact of Chemical Reaction on MHD 3D Flow of a Nanofluid Containing Gyrotactic Microorganism in the Presence of Uniform Heat Source/Sink
- Impact of Dense Internals on Fluid Dynamic Parameters in Bubble Column
- Improvement of Quality and Digestibility of Moringa Oleifera Leaves Feed via Solid-State Fermentation by Aspergillus Niger
- Adsorption of Hexavalent Chromium by Eucalyptus camaldulensis bark/maghemite Nano Composite