Experimental and Computational Studies of Aerated Stirred Tank with Dual Impeller
-
Shivanand M. Teli
,
Viraj S. Pawar
Abstract
Stirred tanks are commonly used in chemical and allied industries for reaction and separation. In order to improve the mixing performance, large scale reactors are often equipped with multiple impellers. In the case of gas-liquid systems, the gas hold-up, mass transfer coefficient, and interfacial area strongly depend on the size and type of impellers, clearance between impellers and superficial gas velocity. In the present work, the effect of the impeller speed, superficial gas velocity, and top impeller position has been investigated on gas hold-up, interfacial area, and mass transfer coefficient. Computational fluid dynamics have been carried out for the multiphase multi-impeller system and the model predictions have been compared with the experimental data.
Acknowledgements
The authors thankfully acknowledge the financial support provided by the Gharda Institute of Technology for this project. Special thanks to the workshop superintendent, Mr A. S. Desai and Prof P.V. Jadhav for helping in the design of the stirred tank reactor in the lab scale.
Nomenclature
- Symbols
- a
Major axis of the ellipse, mm
- b
Minor axis of the ellipse, mm
- c*
Saturation concentration, mg/l
- co
Initial concentration, mg/l
- c
Concentration at specific time instance, mg/1
- C1
Impeller configuration 1
- C2
Impeller configuration 2
- C
Impeller clerance, m
Normalized clearance of impeller (–)
- deq
Equivalent diameter, mm
- dB
Sauter mean bubble diameter, mm
- D
Impeller diameter, m
- dBi
Diameter of bubbles of size class i, mm
- Fi
Volumetric force, N/m3
- g
Acceleration due to gravity, m2/s
- H
Height of the tank, m
- h
Local height of the tank, m
- I
Unit tensor
- J
Piecewise function (–)
- KLa
Volumetric mass transfer coefficient, s-1
- K
Experiential constant eq. (19)
- k
Turbulent kinetic energy, m2/s2
- N
Impeller speed, min-l
Number of the bubbles of size class i
- p
Pressure, N/m2
- PG
Total specific power consumption, w
- pg
Impeller power draw, w
- ∆PO
Static pressure in the absence of gas, psi
- ∆P
Dynamic pressure presence of gas, psi
- Qg
Volumetric gas flow rate, m3/s
- Ri
Interphase force, N/m3
- T
Vessel diameter, m
- t
Time, sec
- ul
Mean velocity of the liquid, m/s
- ug
Mean velocity of the gas, m/s
- Ug
Superficial gas velocity, m/s
- Ul
Superficial liquid velocity, m/s
- V1
Total fluid volume, m3
- Greek Symbols
Empirical constant values eq. (23) & (27)(–)
Empirical constant values eq. (23) & (27)(–)
Empirical constant values eq. (23) & (27)(–)
Empirical constant values eq. (23) & (27)(–)
- Cμ
Constant k-ε Model, eq. (16)
- Cє1
Constant k-ε Model, eq. (15)
- Cє2
Constant k-ε Model, eq. (15)
- σK
Constant k-ε Model, eq. (14)
- σє
Constant k-ε Model, eq. (15)
- εg
Gas hold-up (–)
- εl
Liquid hold-up (–)
- ψ
Aspect ratio (–)
- τ
Torque, N. m
- σ
Surface tension, kg/s2
- ρl
Density of liquid, kg/m3
- ρg
Density of water, kg/m3
- µ
Dynamic viscosity, m2/s
- CD
Drag coefficient in turbulent liquid (–) eq. (19)
- Subscripts
- b, B
Bubble
- g
Gas
- l, L
Liquid
- o
Initial
Abbreviations
- do
Dissolved oxygen meter
- STRs
Stirrer tank reactor
- ReB
Bubble Reynolds number
- Re
Impeller Reynolds number
- EO
Eotos number
- FlG
Gas flow number
- Fr
Froude number
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Artikel in diesem Heft
- Articles
- A Facile Approach to Develop Rice Husk Derived Green Catalyst for One-pot Synthesis of Glycerol Carbonate from Glycerol
- Experimental and Computational Studies of Aerated Stirred Tank with Dual Impeller
- Modified SRK Equation of State for Modeling Asphaltene Precipitation
- Effect of Swirl on Gasification Characteristics in an Entrained-flow Coal Gasifier
- A Novel Micromixer with Fractal Obstacles Designed Based on Generalized Murray’s Law
- Numerical Simulation of A Cubic Spout-Fluid Bed: Influences of Inlet Gas Temperature and Jet to Bed Cross-Section Ratio
- Effect of Competitive Adsorbates on the Catalytic Activity of H3PMo12O40@C in the Oxidation of NMST to NMSBA
- Full-Scale CFD Modeling of Multiphase Flow Distribution in a Packed-bed Absorber with Structured Packing Mellapak 250Y
- Adsorption/desorption, Kinetics and Equilibrium Studies for the Uptake of Cu(II) and Zn(II) onto Banana Peel
- Investigation of Heat Transfer Efficiency of Improved Intermig Impellers in a Stirred Tank Equipped with Vertical Tubes
