A numerical study of mixing intensification for highly viscous fluids in multistage rotor–stator mixers

doi:10.1016/j.cjche.2021.08.012

Abstract

Abstract: How to achieve uniform mixing of highly viscous fluids with low energy consumption is a major industry demand and one of the hot spots of mixing research. A typical multistage rotor-stator mixer (MRSM) equipped with a distributor was investigated to disclose the effects on the mixing performance and power consumption for highly viscous fluids via numerical simulation, considering the influence factors associated with different geometric parameters of both MRSM and the distributor. The mixing index and power consumption are used to evaluate the performance of the mixers. The dimensionless correlations for the mixing index and the power consumption are established considering the factors including the flow rate, rotor speed, the number of mixing units. Adopting the optimized mixer with the distributor (X1-T1), the mixing index increases to 0.85 (obviously higher than 0.46 for the mixer T1 without a distributor), meanwhile the corresponding power consumption is about 1/5 of that of T1 achieving the same mixing effect. It illustrates that the distributor can significantly improve the mixing of highly viscous fluids in the MRSM without the cost of large power consumption. These results would provide a guidance on the design and optimization of multistage rotor-stator mixers in industrial applications.

Key words: Multistage rotor-stator mixer, Computational fluid dynamics, Mixing index, Power consumption, Distributor

摘要： How to achieve uniform mixing of highly viscous fluids with low energy consumption is a major industry demand and one of the hot spots of mixing research. A typical multistage rotor-stator mixer (MRSM) equipped with a distributor was investigated to disclose the effects on the mixing performance and power consumption for highly viscous fluids via numerical simulation, considering the influence factors associated with different geometric parameters of both MRSM and the distributor. The mixing index and power consumption are used to evaluate the performance of the mixers. The dimensionless correlations for the mixing index and the power consumption are established considering the factors including the flow rate, rotor speed, the number of mixing units. Adopting the optimized mixer with the distributor (X1-T1), the mixing index increases to 0.85 (obviously higher than 0.46 for the mixer T1 without a distributor), meanwhile the corresponding power consumption is about 1/5 of that of T1 achieving the same mixing effect. It illustrates that the distributor can significantly improve the mixing of highly viscous fluids in the MRSM without the cost of large power consumption. These results would provide a guidance on the design and optimization of multistage rotor-stator mixers in industrial applications.

关键词: Multistage rotor-stator mixer, Computational fluid dynamics, Mixing index, Power consumption, Distributor

Liying Chen, Junheng Guo, Wenpeng Li, Shuchun Zhao, Wei Li, Jinli Zhang. A numerical study of mixing intensification for highly viscous fluids in multistage rotor–stator mixers[J]. Chinese Journal of Chemical Engineering, 2022, 47(7): 218-230.

References

[1] L. Bouvier, A. Moreau, A. Line, N. Fatah, G. Delaplace, Damage in agitated vessels of large visco-elastic particles dispersed in a highly viscous fluid, J. Food Sci. 76(5)(2011) E384-E391
[2] J.F. Maingonnat, J.L. Doublier, J. Lefebvre, G. Delaplace, Power consumption of a double ribbon impeller with newtonian and shear thinning fluids and during the gelation of a iota-carrageenan solution, J. Food Eng. 87(1)(2008)82-90
[3] M. Migliori, S. Correra, Modelling of dough formation process and structure evolution during farinograph test, Int. J. Food Sci. Technol. 48(1)(2013)121-127
[4] D. Bulnes-Abundis, M.M. Alvarez, The simplest stirred tank for laminar mixing:Mixing in a vessel agitated by an off-centered angled disc, AIChE J. 59(8)(2013)3092-3108
[5] D. Bulnes-Abundis, L.M. Carrillo-Cocom, D. Aráiz-Hernández, A. García-Ulloa, M. Granados-Pastor, P.B. Sánchez-Arreola, G. Murugappan, M.M. Alvarez, A simple eccentric stirred tank mini-bioreactor:Mixing characterization and mammalian cell culture experiments, Biotechnol. Bioeng. 110(4)(2013)1106-1118
[6] J. Dusting, J. Sheridan, K. Hourigan, A fluid dynamics approach to bioreactor design for cell and tissue culture, Biotechnol. Bioeng. 94(6)(2006)1196-1208
[7] X.X. Duan, X. Feng, C. Yang, Z.S. Mao, Numerical simulation of micro-mixing in stirred reactors using the engulfment model coupled with CFD, Chem. Eng. Sci. 140(2016)179-188
[8] F.C. Qiu, Z.H. Liu, R.L. Liu, X.J. Quan, C.Y. Tao, Y.D. Wang, Experimental study of power consumption, local characteristics distributions and homogenization energy in gas-liquid stirred tank reactors, Chin. J. Chem. Eng. 27(2)(2019)278-285
[9] L. Rudolph, M. Schäfer, V. Atiemo-Obeng, M. Kraume, Experimental and numerical analysis of power consumption for mixing of high viscosity fluids with a co-axial mixer, Chem. Eng. Res. Des. 85(5)(2007)568-575
[10] Y.H. Su, G.W. Chen, E.Y. Kenig, An experimental study on the numbering-up of microchannels for liquid mixing, LabChip 15(1)(2015)179-187
[11] H.B. Meng, F. Wang, Y.F. Yu, M.Y. Song, J.H. Wu, A numerical study of mixing performance of high-viscosity fluid in novel static mixers with multitwisted leaves, Ind. Eng. Chem. Res. 53(10)(2014)4084-4095
[12] D.M. Hobbs, F.J. Muzzio, The Kenics static mixer:A three-dimensional chaotic flow, Chem. Eng. J. 67(3)(1997)153-166
[13] S. Wang, J. Wu, N. Ohmura, Inclined-shaft agitation for improved viscous mixing, Ind. Eng. Chem. Res. 52(33)(2013)11741-11751
[14] L.S. Xie, Y.L. Ma, Study on Chaotic mixing process of a two-rotor continuous mixer, China Plast. 23(4)(2009)104-108.(in Chinese)
[15] G.B. Miao, L.S. Xie, H. Tian, Study on mixing index of double rotor continuous mixer, Mod. Manuf. Eng.(6)(2010)126-128, 77.(in Chinese)
[16] X.M. Liu, L.S. Xie, Y.L. Ma, W.F. Cao, Study of dispersive mixing efficiency in mixing section of two-rotor continuous mixer, J. Eng. Plast. Appl. 35(1)(2007)64-68.(in Chinese)
[17] G. Li, L.S. Xie, R.P. Luo, Y.L. Ma, X. Chen, M. Hong, Y.H. Ye, Effects of rotor structures on mixing characteristics of laminated internal mixer, Polymer Mater. Sci. Eng. 30(3)(2014)134-138,143.(in Chinese)
[18] J.T. Jing, L.S. Xie, Y.L. Ma, X. Zhang, Influence of rotor structure and technological parameters on mixing performance of a two-rotor continuous mixer, China Plast. 23(9)(2009)85-90.(in Chinese)
[19] J.T. Jing, L.S. Xie, Y.L. Ma, D.L. Liu, Y.Y. Lu, Statistical analysis on mixing process of a two-rotor continuous mixer, China Plast. 23(2)(2009)93-97.(in Chinese)
[20] G. Gao, L.S. Xie, Y.L. Ma, Y. Liu, T. Chen, Mixing properties of different single screws with Maddock barrier mixers, China Plast. 29(9)(2015)85-91.(in Chinese)
[21] A. Iranshahi, M. Heniche, F. Bertrand, P.A. Tanguy, Numerical investigation of the mixing efficiency of the Ekato Paravisc impeller, Chem. Eng. Sci. 61(8)(2006)2609-2617
[22] A. Kazemzadeh, F. Ein-Mozaffari, A. Lohi, L. Pakzad, Investigation of hydrodynamic performances of coaxial mixers in agitation of yield-pseudoplasitc fluids:Single and double central impellers in combination with the anchor, Chem. Eng. J. 294(2016)417-430
[23] W.K. Cheng, Y. Ye, S.X. Jiang, J.J. Wang, X.P. Gu, L.F. Feng, Mixing intensification in a horizontal self-cleaning twin-shaft kneader with a highly viscous Newtonian fluid, Chem. Eng. Sci. 201(2019)437-447
[24] B.Q. Liu, Y.K. Zhang, M.Q. Chen, P. Li, Z.J. Jin, Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller, Chin. J. Chem. Eng. 23(1)(2015)1-6
[25] W.H. Guo, J.Z. Pan, H.P. Xu, G.W. Tan, Numerical simulation for performance of coaxial stirred tank, J. East China Univ. Techno. Nat. Sci. Ed. 35(3)(2009)486-491.(in Chinese)
[26] W.P. Zhang, X. Wang, X. Feng, C. Yang, Z.S. Mao, Investigation of mixing performance in passive micromixers, Ind. Eng. Chem. Res. 55(38)(2016)10036-10043
[27] M. Rahimi, N. Azimi, M.A. Parsamogadam, A. Rahimi, M.M. Masahy, Mixing performance of T, Y, and oriented Y-micromixers with spatially arranged outlet channel:evaluation with Villermaux/Dushman test reaction, Microsyst. Technol. 23(8)(2017)3117-3130
[28] T. Scherr, S. Pursley, W. Todd Monroe, K. Nandakumar, A numerical study on the loading of cryoprotectant cocktails-on-a-chip, Part I:Interacting miscible viscous fluids, Int. J. Heat Mass Transf. 78(2014)1284-1291
[29] H.Y. Qin, C. Zhang, Q. Xu, X.H. Dang, W. Li, K.L. Lei, L.T. Zhou, J.L. Zhang, Geometrical improvement of inline high shear mixers to intensify micromixing performance, Chem. Eng. J. 319(2017)307-320
[30] W.P. Li, F.S. Xia, S.C. Zhao, J.H. Guo, M.Q. Zhang, W. Li, J.L. Zhang, Mixing performance of an inline high-shear mixer with a novel pore-array liquid distributor, Ind. Eng. Chem. Res. 58(44)(2019)20213-20225
[31] M. Zhang, A safe mixer for highly viscous concentrated liquids, CN Pat., 201811083855.X (2018).(in Chinese)
[32] Y.J. Liu, A mixing apparatus, CN Pat., 201420787175.7(2014).(in Chinese).
[33] I. Nicorescu, C. Vial, C. Loisel, A. Riaublanc, G. Djelveh, G. Cuvelier, J. Legrand, Influence of protein heat treatment on the continuous production of food foams, Food Res. Int. 43(6)(2010)1585-1593
[34] I. Narchi, C. Vial, M. Labbafi, G. Djelveh, Comparative study of the design of continuous aeration equipment for the production of food foams, J. Food Eng. 102(2)(2011)105-114
[35] S. Jabarkhyl, M. Barigou, S.P. Zhu, P. Rayment, D.M. Lloyd, D. Rossetti, Foams generated from viscous non-Newtonian shear-thinning liquids in a continuous multi rotor-stator device, Innov. Food Sci. Emerg. Technol. 59(2020)102231
[36] F. Augier, S. Mezdour, E. Séguineau de Préval, P. Granda, G. Cuvelier, F. Ducept, Impact of interfacial characteristics on foam structure:Study on model fluids and at pilot scale, Oil Gas Sci. Technol. 72(2)(2017)13
[37] L.X. Sun, A high efficiency mixing tank, CN Pat., 201420378606.4(2014).(in Chinese)
[38] H.S. Wu, S.L. Shu, N. Yang, G.P. Lian, S.P. Zhu, M.Y. Liu, Modeling of power characteristics for multistage rotor-stator mixers of shear-thinning fluids, Chem. Eng. Sci. 117(2014)173-182
[39] A. Kazemzadeh, F. Ein-Mozaffari, A. Lohi, L. Pakzad, Intensification of mixing of shear-thinning fluids possessing yield stress with the coaxial mixers composed of two different central impellers and an anchor, Chem. Eng. Process.:Process. Intensif. 111(2017)101-114
[40] A.B.J. Kroezen, J.G. Wassink, E. Bertlein, Foam generation in a rotor-stator mixer, Chem. Eng. Process.:Process. Intensif. 24(3)(1988)145-156
[41] M.C. He, W. Li, M.Q. Zhang, J.L. Zhang, Numerical investigation on the efficient mixing of overbridged split-and-recombine micromixer at low Reynolds number, Microsyst. Technol. 25(9)(2019)3447-3461
[42] X.Y. Chen, J.N. Shen, Numerical analysis of mixing behaviors of two types of E-shape micromixers, Int. J. Heat Mass Transf. 106(2017)593-600
[43] S. Hossain, A. Fuwad, K.Y. Kim, T.J. Jeon, S.M. Kim, Investigation of mixing performance of two-dimensional micromixer using Tesla structures with different shapes of obstacles, Ind. Eng. Chem. Res. 59(9)(2020)3636-3643
[44] W. Raza, S. Hossain, K.Y. Kim, Effective mixing in a short serpentine split-and-recombination micromixer, Sensor Actuat. B:Chem. 258(2018)381-392
[45] V. Viktorov, M.R. Mahmud, C. Visconte, Design and characterization of a new H-C passive micromixer up to Reynolds number 100, Chem. Eng. Res. Des. 108(2016)152-163
[46] J. Aubin, C. Xuereb, Design of multiple impeller stirred tanks for the mixing of highly viscous fluids using CFD, Chem. Eng. Sci. 61(9)(2006)2913-2920
[47] A. Alam, K.Y. Kim, Mixing performance of a planar micromixer with circular Chambers and crossing constriction channels, Sensor Actuat. B:Chem. 176(2013)639-652
[48] D. Patel, F. Ein-Mozaffari, M. Mehrvar, Improving the dynamic performance of continuous-flow mixing of pseudoplastic fluids possessing yield stress using Maxblend impeller, Chem. Eng. Res. Des. 90(4)(2012)514-523
[49] E.S. Szalai, P. Arratia, K. Johnson, F.J. Muzzio, Mixing analysis in a tank stirred with Ekato Intermig^® impellers, Chem. Eng. Sci. 59(18)(2004)3793-3805