Research on motion and mixing of binary particles in rotary kiln installed with unfixed internals

doi:10.16085/j.issn.1000-6613.2017-1046

Abstract

Abstract: The motion and mixing of large particles and small particles in rotary kiln installed with unfixed internals was simulated with discrete element method(DEM). The motion trajectories and motion mode of particles were investigated when installing unfixed internals of different lengths(the rotational speed of rotary kiln,the width and thickness of unfixed internals were constant). The contact number index was used to compare the mixing degree of binary particles in rotary kiln installed unfixed internals of different lengths. The results indicated that when the lengths of unfixed internals were 0,13mm,21mm,29mm and 37mm,the longer the length,the larger the ergodic region of tracer particle's motion trajectory,the smaller the difference of sparse area and dense area of tracer particle's motion trajectory. The tracer particle's motion trajectory was more disorder when installing unfixed internals. The motion mode of particles transformed from rolling to slumping due to the existence of unfixed internals. The disturbance and stirring of unfixed internals could enhance the mixing of large particles and small particles effectively. There is an optimal length of unfixed internals for enhancing mixing of binary particles.

Key words: rotary kiln, binary particles, unfixed internals, mixing degree

摘要： 采用离散单元法（DEM）对内置活动内构件回转窑内二元颗粒的运动混合进行了数值模拟。探讨了添加不同长度活动内构件时（回转窑转速、活动内构件宽度及厚度均固定）示踪颗粒的运动轨迹以及颗粒整体的运动模式。用接触数指标来定量评价颗粒的混合程度，比较了添加不同长度活动内构件时回转窑内二元颗粒的混合程度。结果表明：当活动内构件长度分别为0、13mm、21mm、29mm和37mm时，长度越长，示踪颗粒运动轨迹的遍历区域越大，运动轨迹稀疏区和密集区的差别越小，比起无内构件，添加活动内构件时颗粒的运动方向更加随机，运动轨迹更加紊乱。因活动内构件的存在，颗粒的运动模式由滚落模式变为阶梯模式。活动内构件的扰动和搅拌作用可以有效增强二元颗粒之间的混合。活动内构件存在一个最优长度，过长或过短都不能获得最理想的增混效果。

关键词: 回转窑, 二元颗粒, 活动内构件, 混合程度

CLC Number:

TQ051

ZHANG Lidong, WEI Qingwen, LI Lianhao, WANG Qing, LI Shaohua, QIN Hong. Research on motion and mixing of binary particles in rotary kiln installed with unfixed internals[J]. Chemical Industry and Engineering Progress, 2018, 37(03): 845-852.

张立栋, 韦庆文, 李连好, 王擎, 李少华, 秦宏. 内置活动内构件回转窑内二元颗粒的运动混合研究[J]. 化工进展, 2018, 37(03): 845-852.

References

[1] 刘扬,韩燕龙,贾富国,等. 椭球颗粒搅拌运动及混合特性的数值模拟研究[J]. 物理学报,2015,64(11):264-271. LIU Y,HAN Y L,JIA F G,et al. Numerical simulation on stirring motion and mixing characteristics of ellipsoid particles[J]. Acta Physica Sinica,2015,64(11):264-271.
[2] SHI Q,SUN G,HOU M,et al. Density-driven segregation in vertically vibrated binary granular mixtures[J]. Physical Review E,2007,75(6):061302.
[3] SHI Q,YAN X,HOU M,et al. Experimental study of segregation patterns in binary granular mixtures under vertical vibration[J]. Science Bulletin,2003,48(7):627-629.
[4] LIU R,LI Y,HOU M. Oscillatory phenomena of compartmentalized bidisperse granular gases[J]. Physical Review E,2009,79(5):052301.
[5] 贺实月,李会泉,李少鹏,等. 煤粉炉高铝粉煤灰碱溶脱硅反应动力学[J]. 中国有色金属学报,2014,24(7):1888-1894. HE S Y,LI H Q,LI S P,et al. Kinetics of desilication process of fly ash with high aluminum from pulverized coal fired boiler in alkali solution[J]. The Chinese Journal of Nonferrous Metals,2014,24(7):1888-1894.
[6] 李少华,张立栋,余侃胜,等. 回转干馏炉内油页岩颗粒群断续给料混合运动模式[J]. 化工进展,2010,29(8):1433-1437. LI S H,ZHANG L D,YU K S,et al. Experimentals on mixed motion with discontinuous feed for oil shale particle group in rotary kiln[J]. Chemical Industry and Engineering Progress,2010,29(8):1433-1437.
[7] 张立栋,王丽伟,朱明亮,等. 回转干馏炉内油页岩与固体热载体颗粒轴向混合特性实验[J]. 东北电力大学学报,2012,32(6):63-66. ZHANG L D,WANG L W,ZHU M L,et al. Experimental on axis mixing degree of oil shale with solid heat carrier particles in rotary retorting[J]. Journal of Northeast Dianli University,2012,32(6):63-66.
[8] 王擎,肖冠华,孔祥钊,等. 固体热载体干馏桦甸油页岩试验研究[J]. 东北电力大学学报,2013,33(5):15-21. WANG Q,XIAO G H,KONG X Z,et al. Experimental investigation of solid heat carrier retorting of huadian oil shale[J]. Journal of Northeast Dianli University,2013,33(5):15-21.
[9] 何继来,王擎. 爱沙尼亚葛洛特干馏技术的发展与应用[J]. 东北电力大学学报,2016,36(2):76-80. HE J L,WANG Q. Development and application of Estonia Galoter technology[J]. Journal of Northeast Dianli University,2016,36(2):76-80.
[10] 金辉霞,栢娜,杨格兰. 滚筒内颗粒混合过程的DEM仿真研究[J]. 控制工程,2013,20(3):566-570. JIN H X,BAI N,YANG G L. The DEM simulation study of the particle mixing process in the rotating cylinder[J]. Control Engineering of China,2013,20(3):566-570.
[11] 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,2015,27:864-870.
[12] NITYANAND N,MANLEY B,HENEIN H. An analysis of radial segregation for different sized spherical solids in rotary cylinders[J]. Metallurgical and Materials Transactions B,1986,17:247-257.
[13] 陶贺,钟文琪,金保昇. 采用多元颗粒模型对圆柱形颗粒在移动床中流动的离散单元法直接数值模拟[J]. 中国电机工程学报,2012,32(17):13-19. TAO H,ZHONG W Q,JIN B S. Discrete element modeling of cylindrical particle flowing in the moving bed by multi-element particle model[J]. Proceedings of the CSEE,2012,32(17):13-19.
[14] SUNKARA K R,HERZ F,SPECHT E,et al. Transverse flow at the flight surface in flighted rotary drum[J]. Powder Technology,2015,275:161-171.
[15] BHATTACHARYA T,HAJRA S K,MCCARTHY J J. A design heuristic for optimizing segregation avoidance practices in horizontal drum mixers[J]. Powder Technology,2014,253:107-115.
[16] ZHOU Z X,LI J H,ZHOU J Z,et al. Enhancing mixing of cohesive particles by baffles in a rotary drum[J]. Particuology,2015,25:104-110.
[17] 赵永志,张宪旗,刘延雷,等. 滚筒内非等粒径二元颗粒体系增混机理研究[J]. 物理学报,2009,58(12):8386-8393. ZHAO Y Z,ZHANG X Q,LIU Y L,et al. Augmenting the mixing of size-type binary granular systems in a rotating horizontal drum[J]. Acta Physica Sinica,2009,58(12):8386-8393.
[18] SCHERER V,MÖNNIGMANN M,BERNER M O,et al. Coupled DEM-CFD simulation of drying wood chips in a rotary drum-Baffle design and model reduction[J]. Fuel,2016,184:896-904.
[19] KARALI M A,HERZ F,SPECHT E,et al. Comparison of image analysis methods to determine the optimum loading of flighted rotary drums[J]. Powder Technology,2016,291:147-153.
[20] LI M,LING X,PENG H,et al. An investigation on heat transfer of granular materials in the novel flighted rotary drum[J]. Canadian Journal of Chemical Engineering,2017,95:386-397.
[21] YU F,ZHOU G,XU J,et al. Enhanced axial mixing of rotating drums with alternately arranged baffles[J]. Powder Technology,2015,286:276-287.
[22] 王丽伟,李少华,孙旭光,等. 一种工业用回转窑:103743227B[P]. 2015-07-08. WANG L W,LI S H,SUN X G,et al. Industrial rotary kiln:CN103743227B[P]. 2015-07-08.
[23] 陈辉,刘义伦,赵先琼,等. 一元散体颗粒物料在回转窑截面上的运动与混合[J]. 中国有色金属学报,2015,25(5):2575-2581. CHEN H,LIU Y L,ZHAO X Q,et al. Motion and mixing of mono-disperse granular material in cross section of rotary kiln[J]. The Chinese Journal of Nonferrous Metals,2015,25(5):2575-2581.
[24] 张立栋,李少华,朱明亮,等. 回转干馏炉内抄板形式与双组元颗粒混合过程冷模数值研究[J]. 中国电机工程学报,2012,32(11):72-78. ZHANG L D,LI S H,ZHU M L,et al. Cold mode numerical analysis of flights forms and two component particles mixing in rotary retorting[J]. Proceedings of the CSEE,2012,32(11):72-78.
[25] 张立栋,韦庆文,秦宏,等. 柱状生物质颗粒与钢球颗粒在滚筒中的混合特性[J]. 化工进展,2016,35(10):3057-3064. ZHANG L D,WEI Q W,QIN H,et al. Mixing characteristics in a rotary drum filled with cylindrical biomass and spherical steel particles[J]. Chemical Industry and Engineering Progress,2016,35(10):3057-3064.
[26] CUNDALL P A,STRACK O L. A discrete numerical model for granular assemblies[J]. Geotechnique,1979,29(1):47-65.
[27] 陶贺,钟文琪,金保昇,等. 异径混合非球形颗粒在移动床中流动特性的数值模拟[J]. 科学通报,2015,60(27):2667-2675. TAO H,ZHONG W Q,JIN B S,et al. Numerical simulation of flow characteristics for non-spherical particle mixture flowing in moving bed[J]. Chin. Sci. Bull.,2015,60(27):2667-2675.
[28] MELLMANN J. The transverse motion of solids in rotating cylinders-Forms of motion and transition behaviour[J]. Powder Technology,2001,118:251-270.
[29] OTTINO J M,KHAKHAR D V. Mixing and segregation of granular materials[J]. Annual Review of Fluid Mechanics,2000,32(1):55-91.
[30] GUPTA A,KATTERFELD A,SOETEMAN B,et al. Discrete element study mixing in an industrial sized mixer[C]//World Congress on Particle Technology 6,Nürnberg Messe Gmbh,2010.