The effects of different types of screws on granular mixing in a double-screw conical mixer were investigated by discrete element method (DEM). Specifically, the effects of the pitch diameter ratio (the ratio of the pitch to the diameter of the screw) and the screw diameter ratio (the ratio of the short screw diameter to the long screw diameter) on the mixing efficiency, device power and wear rate of the device were studied. Results show that different types of screws will affect the granular mixing, the device power as well as the device wear, however, the particles all can be well mixed after 100 s in the double-screw conical mixer with different screws. When other parameters remain unchanged, with the screw diameter ratio increasing, the mixing efficiency keeps similar, and the device power increases, but the wear rate of the device decreases. With the screw diameter ratio increasing, the mixing efficiency increases, and the device power increases, but the wear rate of the device fluctuates within a certain range.
Rui-huan CAI,Yong-zhi ZHAO. Effect of screw structure on granular mixing in a double-screw conical mixer. Journal of ZheJiang University (Engineering Science), 2021, 55(11): 2067-2075.
Tab.1Parameters used in simulations for double-screw conical mixer
算例编号
P1/mm
P2/mm
D1/mm
D2/mm
P1/D1=P2/D2
D2/D1
1
90
112.5
120
150
0.75
1.25
2
120
150.0
120
150
1.00
1.25
3
150
187.5
120
150
1.25
1.25
4
180
225.0
120
150
1.50
1.25
5
210
262.5
120
150
1.75
1.25
6
150
187.5
120
90
1.25
0.75
7
150
187.5
120
120
1.25
1.00
8
150
187.5
120
180
1.25
1.50
9
150
187.5
120
210
1.25
1.75
Tab.2Simulation cases for double-screw conical mixer
Fig.2Comparison of geometries of different screws
Fig.3Simulated snapshots of front view of granular mixing condition for case 3
Fig.4Simulated axial snapshots of granular mixing condition for cases 1，3 and 5
Fig.5Simulated axial snapshots of granular mixing condition for cases 6，3 and 9
Fig.6Mixing index versus time for different cases
Fig.7Device power for different cases
Fig.8Wear rate for different cases
[1]
NOROUZI H, ZARGHAMI R, MOSTOUFI N Insights into the granular flow in rotating drums[J]. Chemical Engineering Research and Design, 2015, 102: 12- 25
doi: 10.1016/j.cherd.2015.06.010
[2]
YAMAMOTO M, ISHIHARA S, KANO J Evaluation of particle density effect for mixing behavior in a rotating drum mixer by DEM simulation[J]. Advanced Powder Technology, 2016, 27 (3): 864- 870
doi: 10.1016/j.apt.2015.12.013
[3]
赵永志, 程易 水平滚筒内二元颗粒体系径向分离模式的数值模拟研究[J]. 物理学报, 2008, 57 (1): 322- 328 ZHAO Yong-zhi, CHENG Yi Numerical simulation of radial segregation patterns of binary granular systems in a rotating horizontal drum[J]. Acta Physica Sinica, 2008, 57 (1): 322- 328
doi: 10.3321/j.issn:1000-3290.2008.01.052
[4]
CHANDRATILLEKE G, YU A, STEWART R, et al Effects of blade rake angle and gap on particle mixing in a cylindrical mixer[J]. Powder Technology, 2009, 193 (3): 303- 311
doi: 10.1016/j.powtec.2009.03.007
[5]
ALIAN M, EIN-MOZAFFARI F, UPRETI S Analysis of the mixing of solid particles in a plowshare mixer via discrete element method (DEM)[J]. Powder Technology, 2015, 274: 77- 87
doi: 10.1016/j.powtec.2015.01.012
[6]
SAKAI M, SHIGETO Y, BASINSKAS G, et al Discrete element simulation for the evaluation of solid mixing in an industrial blender[J]. Chemical Engineering Journal, 2015, 279: 821- 839
doi: 10.1016/j.cej.2015.04.130
[7]
LIU P, YANG R, YU A DEM study of the transverse mixing of wet particles in rotating drums[J]. Chemical Engineering Science, 2013, 86: 99- 107
doi: 10.1016/j.ces.2012.06.015
[8]
BRONE D, ALEXANDER A, MUZZIO F Quantitative characterization of mixing of dry powders in V-blenders[J]. AICHE Journal, 1998, 44 (2): 271- 278
doi: 10.1002/aic.690440206
[9]
KUO H, KNIGHT P, PARKER D, et al The influence of DEM simulation parameters on the particle behaviour in a V-mixer[J]. Chemical Engineering Science, 2002, 57 (17): 3621- 3638
doi: 10.1016/S0009-2509(02)00086-6
[10]
MOLAEI E A, YU A B, ZHOU Z Y Particle scale modelling of mixing of ellipsoids and spheres in gas-fluidized beds by a modified drag correlation[J]. Powder Technology, 2019, 343: 619- 628
doi: 10.1016/j.powtec.2018.11.054
[11]
张勇, 金保升, 钟文琪 喷动气固流化床颗粒混合规律的实验研究[J]. 中国电机工程学报, 2008, 28 (20): 8- 12 ZHANG Yong, JIN Bao-sheng, ZHONG Wen-qi Experimental investigation on particle mixing in spout-fluid bed[J]. Proceedings of the CSEE, 2008, 28 (20): 8- 12
doi: 10.3321/j.issn:0258-8013.2008.20.002
[12]
马华庆, 赵永志 喷动流化床中杆状颗粒混合特性的CFD-DEM模拟[J]. 浙江大学学报: 工学版, 2020, 54 (7): 1347- 1354 MA Hua-qing, ZHAO Yong-zhi CFD-DEM investigation on mixing of rod-like particles in spout-fluid bed[J]. Journal of Zhejiang University: Engineering Science, 2020, 54 (7): 1347- 1354
[13]
BERGH W, SCARLETT B, KOLAR Z. Computer simulation model of a nauta mixer [J]. Powder Technology, 1993, 77(1): 19-30.
[14]
BERNTSSON O, DANIELSSON L, LAGERHOLM B, et al Quantitative in-line monitoring of powder blending by near infrared reflection spectroscopy[J]. Powder Technology, 2002, 123 (2/3): 185- 193
[15]
GOLSHAN S, ZARGHAMI R, NOROUZI H N, et al Granular mixing in nauta blenders[J]. Powder Technology, 2017, 305: 279- 288
doi: 10.1016/j.powtec.2016.09.059
[16]
BEDNAREK X, MARTIN S, NDIAYE A, et al Extrapolation of DEM simulations to large time scale. application to the mixing of powder in a conical screw mixer[J]. Chemical Engineering Science, 2019, 197: 223- 234
doi: 10.1016/j.ces.2018.12.022
[17]
王凯, 虞军. 化工设备设计全书: 搅拌设备[M]. 北京: 化学工业出版社, 2003.
[18]
QI F, HEINDEL T, WRIGHT M Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method[J]. Powder Technology, 2017, 308: 334- 345
doi: 10.1016/j.powtec.2016.12.043
[19]
BAO Y, LI T, WANG D, et al Discrete element method study of effects of the impeller configuration and operating conditions on particle mixing in a cylindrical mixer[J]. Particuology, 2020, 49: 146- 158
doi: 10.1016/j.partic.2019.02.002
[20]
BAO Y, LU Y, CAI Z, et al Effects of rotational speed and fill level on particle mixing in a stirred tank with different impellers[J]. Chinese Journal of Chemical Engineering, 2018, 26 (6): 1383- 1391
doi: 10.1016/j.cjche.2017.11.010
[21]
OSORIO J, MUZZIO F Effects of processing parameters and blade patterns on continuous pharmaceutical powder mixing[J]. Chemical Engineering and Processing, 2016, 109: 59- 67
doi: 10.1016/j.cep.2016.07.012
[22]
CAI R, HOU Z, ZHAO Y Numerical study on particle mixing in a double-screw conical mixer[J]. Powder Technology, 2019, 352: 193- 208
doi: 10.1016/j.powtec.2019.04.065
[23]
CAI R, ZHAO Y An experimentally validated coarse-grain DEM study of monodisperse granular mixing[J]. Powder Technology, 2020, 361: 99- 111
doi: 10.1016/j.powtec.2019.10.023
[24]
CUNDALL P A, STRACK O D A discrete numerical model for granular assemblies[J]. Geotechnique, 1979, 29 (1): 47- 65
doi: 10.1680/geot.1979.29.1.47
[25]
TING J M, CORKUM B T Computational laboratory for discrete element geomechanics[J]. Journal of Computing in Civil Engineering, 1992, 6 (2): 129- 146
doi: 10.1061/(ASCE)0887-3801(1992)6:2(129)
[26]
LACEY P M C Developments in the theory of particle mixing[J]. Journal of Applied Chemistry, 1954, 4 (5): 257- 268
[27]
XU L, LUO K, ZHAO Y Numerical prediction of wear in SAG mills based on DEM simulations[J]. Powder Technology, 2018, 329: 353- 363
doi: 10.1016/j.powtec.2018.02.004
[28]
许磊, 罗坤, 赵永志, 等. 物料粒径对半自磨机衬板磨损的影响[J]. 浙江大学学报: 工学版, 2019, 53 (12): 2255- 2263 XU Lei, LUO Kun, ZHAO Yong-zhi, et al Effect of particle size on liner wear in semi-autogenous mill[J]. Journal of Zhejiang University: Engineering Science, 2019, 53 (12): 2255- 2263
doi: 10.3785/j.issn.1008-973X.2019.12.001
[29]
FINNIE I Erosion of surfaces by solid particles[J]. Wear, 1960, 3 (2): 87- 103
doi: 10.1016/0043-1648(60)90055-7
