CFD Analysis and Design Optimization in a Curved Blade Impeller
-
Nazila Sutudehnezhad
Abstract
Mixing efficiency in stirred tank reactors is an important challenge in the design of many industrial processes. The effect of blade shape on mixing efficiency has been studied in the present work. The computational method has been used to investigate the flow field, power consumption, pumping capacity, hydraulic efficiency, and mixing time in a fully baffled tank stirred by a Rushton turbine and different curved blade impellers. Flow in a stirred tank reactor involves interactions between flow around rotating blades and stationary baffles. The flow field was developed using the sliding mesh (SM) approach in computational fluid dynamics (CFD). The realizable k-ε was used to model the turbulence. A reasonable agreement between the experimental reported data and simulation results indicated the validity of CFD model. It has been revealed that increasing the blade curvature, at approximately the same mixing time would enhance the mixing efficiency up to 61.3 % in comparison with the Rushton turbine. This mixing efficiency would favor the employment of curved blade impellers due to the cost-benefits of stirred tank operations.
Nomenclature
- A
area (m2)
- w
blade height (m)
- C
mean concentration of species (kg/m3)
- C′
fluctuating tracer concentration (µg/l)
- C∞
final tracer concentration (µg/l)
- C1
clearance of impeller (m)
- d
distance of computational cell from the closest wall (m)
- D
outer diameter of the impeller (m)
- x
Disc thickness (m)
- D0
Disc diameter (m)
- (B-C)
Blade depression
- t
Impeller blade thickness
- wbaffle
baffle width (m)
- N
impeller rotational speed (s−1)
- Np
power number
- Nq
pumping number
- Δp
pressure difference (Pa)
- Qp
impeller pumping capacity (m3/s)
- Qr
radial pumping flow rate of the impeller (m3/s)
- r
radial direction (m)
- R
impeller radius (m)
- Re
impeller Reynolds number
- t95
pixel mixing time (s)
- T
tank diameter (m)
- V
mean velocity vector (m/s)
- vtip
impeller tip velocity (m/s)
average radial velocity at the blade tip over the height of blade(m/s)
- x, y, z
coordinate vector (m)
Greek letters
- ρ
liquid density (kg/m3)
- µ
liquid viscosity (Pa s)
- Γ
torque (Nm)
- σt
turbulent Schmidt number
- μt
turbulent viscosity (kg m−1s−1)
kinetic energy dissipation rate
mixing efficiency
References
1. Afshar Ghotli, R., Abdul Aziz, A.R., Ibrahim, Sh., Baroutian, S., Arami-Niya, A., 2013. Study of various curved-blade impeller geometries on power consumption in stirred vessel using response surface methodology. Journal of the Taiwan Institute of Chemical Engineers 44, 192–201.10.1016/j.jtice.2012.10.010Suche in Google Scholar
2. Amanullah, A., Serrano-Carreon, L., Castro, B., Galindo, E., Nienow, A.W., 1998. The influence of impeller type in pilot scale Xanthan fermentations. Biotechnology Bioengineering 57(1), 95–108.10.1002/(SICI)1097-0290(19980105)57:1<95::AID-BIT12>3.0.CO;2-7Suche in Google Scholar
3. Ammar, M., Chtourou, W., Driss, Z., Abid, M.S., 2011. Numerical investigation of turbulent flow generated in baffled stirred vessels equipped with three different turbines in one and two-stage system. Energy 36, 5081–5093.10.1016/j.energy.2011.06.002Suche in Google Scholar
4. ANSYS FLUENT Theory Guide, Release 15.0, ANSYS, (November 2013).Suche in Google Scholar
5. Bakker, A., Myers, K.J., Ward, R.W., Lee, C.K., 1996. The laminar and turbulent flow pattern of a pitched blade turbine. Chemical Engineering Research and Design 74(4), 485–491.Suche in Google Scholar
6. Chara, Z., Kysela, B., Konfrst, J., Fort, I., 2016. Study of fluid flow in baffled vessels stirred by a Rushton standard impeller. Applied Mathematics and Computation 272, 614–628.10.1016/j.amc.2015.06.044Suche in Google Scholar
7. Chen, Z.D., Chen, J.J.J., 1999. Comparison of mass transfer performance for various single and twin impellers. Chemical Engineering Research and Design 77(2), 104–109.10.1205/026387699525972Suche in Google Scholar
8. Cooke, M., Heggs, P.J., 2005. Advantages of the hollow (concave) turbine for multi-phase agitation under intense operating conditions. Chemical Engineering Science 60(20), 5529–5543.10.1016/j.ces.2005.05.018Suche in Google Scholar
9. Derksen, J.J., Doelman, M.S., Van den Akker, H.E.A., 1999. Three-dimensional LDA measurements in the impeller region of a turbulently stirred tank. Experiments in Fluids 27, 522–532.10.1007/s003480050376Suche in Google Scholar
10. Devi, T.T., Kumar, B., Patel, A.K., 2015. Detached Eddy simulation of turbulent flow in stirred tank reactor. Procedia Engineering 127, 87–94.10.1016/j.proeng.2015.11.430Suche in Google Scholar
11. Fořt, I., Jirout, T., Sperling, R., Jambere, S., Rieger, F., 2002. Study of pumping capacity of pitched blade impellers. Acta Polytechnica 42, 68–72.10.14311/380Suche in Google Scholar
12. Forrester, S.E., Rielly, C.D., Carpenter, K.J., 1998. Gas-inducing impeller design and performance characteristics. Chemical Engineering Science 53(4), 603–15.10.1016/S0009-2509(97)00352-7Suche in Google Scholar
13. Gimbun, J., Rielly, C.D., Nagy, Z.K., Derksen, J.J., 2012. Detached eddy simulation on the turbulent flow in a stirred tank. AIChE Journal 58(10), 3224–3241.10.1002/aic.12807Suche in Google Scholar
14. Houcine, I., Plasari, E., David, R., 2000. Effects of the stirred tank’s design on power consumption and mixing time in liquid phase. Chemical Engineering & Technology 23 (7), 605–613.10.1002/1521-4125(200007)23:7<605::AID-CEAT605>3.0.CO;2-0Suche in Google Scholar
15. Javed, K.H., Mahmud, T., Zhu, J.M., 2006. Numerical simulation of turbulent batch mixing in a vessel agitated by a Rushton turbine. Chemical Engineering and Processing 45, 99–112.10.1016/j.cep.2005.06.006Suche in Google Scholar
16. Jaworski, Z., Zakrzewska, B., 2002. Modeling of the turbulent wall jet generated by a pitched blade turbine impeller—the effect of turbulence model. Chemical Engineering Research and Design 80(8), 846–854.10.1205/026387602321143381Suche in Google Scholar
17. Jing, Z., Zhengming, G., Yuyun, B., 2011. Effects of the blade shape on the trailing vortices in liquid flow generated by disc turbines. Chinese Journal of Chemical Engineering 19(2), 232–242.10.1016/S1004-9541(11)60160-2Suche in Google Scholar
18. Joshi, J.B., Nere, N.K., Rane, C.V., Murthy, B.N., Mathpati, C.S., Patwardhan, A.W., Ranade, V.V., 2011a. CFD simulation of stirred tanks: comparison of turbulence models. Part I: radial flow impellers. The Canadian Journal of Chemical Engineering 89(1), 23–82.10.1002/cjce.20446Suche in Google Scholar
19. Joshi, J.B., Nere, N.K., Rane, C.V., Murthy, B.N., Mathpati, C.S., Patwardhan, A.W., Ranade, V.V., 2011b. CFD simulation of stirred tanks: comparison of turbulence models (Part II: axial flow impellers, multiple impellers and multiphase dispersions). The Canadian Journal of Chemical Engineering 89(4), 754–816.10.1002/cjce.20465Suche in Google Scholar
20. Karcz, J., Major, M., 1998. An effect of a Baffle length on the power consumption in an agitated vessel. Chemical Engineering and Processing 37(3), 249–256.10.1016/S0255-2701(98)00033-6Suche in Google Scholar
21. Khare, A.S., Niranjan, K., 1999. An experimental investigation into the effect of impeller design on gas hold-up in a highly viscous Newtonian liquid. Chemical Engineering Science 54(8), 1093–1100.10.1016/S0009-2509(98)00479-5Suche in Google Scholar
22. Kumaresan, T., Joshi, J.B., 2006. Effect of impeller design on the flow pattern and mixing in stirred tanks. Chemical Engineering Journal 115(3), 173–193.10.1016/j.cej.2005.10.002Suche in Google Scholar
23. Liu, B., Zhang, Y., Chen, M., Li, P., Jin, Z., 2015. Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller. Chinese Journal of Chemical Engineering 23, 1–6.10.1016/j.cjche.2013.09.001Suche in Google Scholar
24. Mavros, P., 2001. Flow visualization in stirred vessels—a review of experimental techniques. Chemical Engineering Research and Design 79(2), 113–127.10.1205/02638760151095926Suche in Google Scholar
25. Mavros, P., Xuereb, C., Bertrand, J., 1998. Determination of 3-D flow fields in agitated vessels by laser Doppler velocimetry: use and interpretation of RMS velocities. Chemical Engineering Research and Design 76(2), 223–233.10.1205/026387698524640Suche in Google Scholar
26. Mhetras, M.B., Pandit, A.B., Joshi, J.B., 1994. Effect of agitator design on hydrodynamics and power consumption in mechanically agitated gas–liquid reactors. In: Eighth European Conference on Mixing, Cambridge, UK, pp. 375–382.Suche in Google Scholar
27. Molnár, B., Egedy, A., Varga, T., 2013. CFD Model based comparison of mixing efficiency of different impeller geometries. Chemical Engineering Transactions 32, 1453–1458.Suche in Google Scholar
28. Nienow, A.W., 1997. On impeller circulation and mixing effectiveness in the turbulent flow regime. Chemical Engineering Science 52(15), 2557–2565.10.1016/S0009-2509(97)00072-9Suche in Google Scholar
29. Oching, A., Onyango, M.S., 2008. Homogenization energy in a stirred tank. Chemical Engineering and Processing 47(9–10), 1853–1860.10.1016/j.cep.2007.10.014Suche in Google Scholar
30. Patwardhan, A.W., Joshi, J.B., 1999. Relation between flow pattern and blending in stirred tanks. Industrial & Engineering Chemistry Research 38(3), 3131–3143.10.1021/ie980772sSuche in Google Scholar
31. Paul, E.L., Atiema-obeng, V.A., Kresta, S.M., 2004. Handbook of Industrial Mixing-Science and Practice, Wiley, Hoboken, NJ.10.1002/0471451452Suche in Google Scholar
32. Ranade, V.V., Mishra, V.P., Saraph, V.S., Deshpande, G.B., Joshi, J.B., 1992. Comparison of axial flow impellers using a laser Doppler anemometer. Industrial & Engineering Chemistry Research 31(10), 2370–2379.10.1021/ie00010a016Suche in Google Scholar
33. Ruszkowski, S., 1994. A rational method for measuring blending performance, ad comparison of different impeller types. In: Proceedings of the 8th European Conference on Mixing, Cambridge, UK, pp. 283–292.Suche in Google Scholar
34. Rutherford, K., Mahmoudi, S., Lee, K.C., Yianneskis, M., 1996. The influence of Rushton impeller blade and disk thickness on the mixing characteristics of stirred vessels. Chemical Engineering Research and Design 74(4), 369–378.Suche in Google Scholar
35. Saito, F., Nienow, A.W., Chatwin, S., Moore, I.P.T., 1992. Power, gas dispersion and homogenization characteristics of SCABA SRGT and Rushton turbine impellers. Journal of Chemical Engineering of Japan 25, 281–287.10.1252/jcej.25.281Suche in Google Scholar
36. Shiue, S.J., Wong, C.W., 1984. Studies on homogenization efficiency of various agitators in liquid blending. The Canadian Journal of Chemical Engineering 62(5), 602–609.10.1002/cjce.5450620505Suche in Google Scholar
37. Singh, H., Fletcher, D.F., Nijdam, J.J., 2011. An assessment of different turbulence models for predicting flow in a baffled tank stirred with a Rushton turbine. Chemical Engineering Science 66(23), 5976–5988.10.1016/j.ces.2011.08.018Suche in Google Scholar
38. Stoots, C.M., Calabrese, R.V., 1995. Mean velocity field relative to a Rushton turbine blade. AIChE Journal 41(1), 1–11.10.1002/aic.690410102Suche in Google Scholar
39. Tatterson, G.R., 2003. Fluid Mixing and Gas Dispersion in Agitated Tanks, McGraw Hill, New York.Suche in Google Scholar
40. Weetman, R.J., Oldshue, J.Y., 1988. Power, flow and shear characteristics of mixing impellers. In: Proceedings of 6th European Conference on Mixing, Pavia, Italy.Suche in Google Scholar
41. Wilcox, D.C., 2006. Turbulence Modeling for CFD. D C W Industries, incorporated, La Cañada Flintridge.Suche in Google Scholar
42. Wu, J., Zhu, Y., Pullum, L., 2001. Impeller geometry effect on velocity and solids suspension. CSIRO Thermal and Fluids Engineering, Victoria, Australia.10.1205/02638760152721857Suche in Google Scholar
43. Wu, H., Patterson, G.K., 1989. Laser-Doppler measurements of turbulent-flow parameters in a stirred mixer. Chemical Engineering Science 44(10), 2207–2221.10.1016/0009-2509(89)85155-3Suche in Google Scholar
44. Yang, F.L., Zhou, S.J., Wang, G.C., 2011. Detached Eddy simulation of the turbulent flow in a stirred tank. Advanced Materials Research 236–238, 1487–1491.10.4028/www.scientific.net/AMR.236-238.1487Suche in Google Scholar
45. Zadghaffari, R., Moghaddas, J.S., Revstedt, J., 2009. A mixing study in a double-Rushton stirred tank. Computer & Chemical Engineering 33(7), 1240–1246.10.1016/j.compchemeng.2009.01.017Suche in Google Scholar
©2017 by De Gruyter
Artikel in diesem Heft
- Bubble Trajectory in a Bubble Column Reactor using Combined Image Processing and Artificial Neural Network
- Non-linear Radiation Effects in Mixed Convection Stagnation Point Flow along a Vertically Stretching Surface
- Mixing Behaviors of Jets in Cross-Flow for Heat Recovery of Partial Oxidation Process
- Selective Hydrogenation of 4’,4”(5”)-Di-Tert-Butyldibenzo-18-Crown-6 Ether over Rh/γ-Al2O3 Nanocatalyst
- Titania-Loaded Coal Char as Catalyst in Oxidation of Styrene with Aqueous Hydrogen Peroxide
- A Study of the Soft-Sphere Model in Eulerian-Lagrangian Simulation of Gas-Liquid Flow
- Conceptual Approach in Multi-Objective Optimization of Packed Bed Membrane Reactor for Ethylene Epoxidation Using Real-coded Non-Dominating Sorting Genetic Algorithm NSGA-II
- Kinetics of Extraction of Tributyl phosphate (TBP) from Aqueous Feed in Single Stage Air-sparged Mixing Unit
- Viscous Dissipation Effects in Water Driven Carbon Nanotubes along a Stream Wise and Cross Flow Direction
- Evaluation of Mixing and Mixing Rate in a Multiple Spouted Bed by Image Processing Technique
- A Parametric Study of Biodiesel Production Under Ultrasounds
- Numerical Study of MHD Viscoelastic Fluid Flow with Binary Chemical Reaction and Arrhenius Activation Energy
- CFD Analysis and Design Optimization in a Curved Blade Impeller
- Bio-Oil Heavy Fraction as a Feedstock for Hydrogen Generation via Chemical Looping Process: Reactor Design and Hydrodynamic Analysis
- Upgrading of Heavy Oil in Supercritical Water using an Iron based Multicomponent Catalyst
Artikel in diesem Heft
- Bubble Trajectory in a Bubble Column Reactor using Combined Image Processing and Artificial Neural Network
- Non-linear Radiation Effects in Mixed Convection Stagnation Point Flow along a Vertically Stretching Surface
- Mixing Behaviors of Jets in Cross-Flow for Heat Recovery of Partial Oxidation Process
- Selective Hydrogenation of 4’,4”(5”)-Di-Tert-Butyldibenzo-18-Crown-6 Ether over Rh/γ-Al2O3 Nanocatalyst
- Titania-Loaded Coal Char as Catalyst in Oxidation of Styrene with Aqueous Hydrogen Peroxide
- A Study of the Soft-Sphere Model in Eulerian-Lagrangian Simulation of Gas-Liquid Flow
- Conceptual Approach in Multi-Objective Optimization of Packed Bed Membrane Reactor for Ethylene Epoxidation Using Real-coded Non-Dominating Sorting Genetic Algorithm NSGA-II
- Kinetics of Extraction of Tributyl phosphate (TBP) from Aqueous Feed in Single Stage Air-sparged Mixing Unit
- Viscous Dissipation Effects in Water Driven Carbon Nanotubes along a Stream Wise and Cross Flow Direction
- Evaluation of Mixing and Mixing Rate in a Multiple Spouted Bed by Image Processing Technique
- A Parametric Study of Biodiesel Production Under Ultrasounds
- Numerical Study of MHD Viscoelastic Fluid Flow with Binary Chemical Reaction and Arrhenius Activation Energy
- CFD Analysis and Design Optimization in a Curved Blade Impeller
- Bio-Oil Heavy Fraction as a Feedstock for Hydrogen Generation via Chemical Looping Process: Reactor Design and Hydrodynamic Analysis
- Upgrading of Heavy Oil in Supercritical Water using an Iron based Multicomponent Catalyst
