回转干馏炉内挡板形状对二元颗粒运动混合的影响
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摘要
根据回转干馏炉(简称回转炉)内二元颗粒混合时的涡心区的位置,提出在距离回转炉中心21 mm处设置挡板的增混方式.挡板主要依靠推送和抛洒2种作用来增强二元颗粒之间的混合.采用离散单元法,对安装不同形状挡板的回转炉内二元颗粒的运动混合进行数值模拟,研究挡板形状对二元颗粒运动混合的影响.结果表明,挡板边数越多,平均终末卸料角越大.在回转炉运行过程中,当挡板边数为2时,仅存在主体颗粒瀑布流;当挡板边数为1、3、4、∞时,主体颗粒瀑布流和悬空颗粒瀑布流共存.相比于无挡板,在回转炉中安装挡板时,不存在小颗粒集中分布的涡心区,2种颗粒交错分布,颗粒分布更加均匀.当挡板边数从0增加到2时,时均接触数指标M的提高比较明显,从0.288增加到0.424,颗粒的混合质量变好.对于2、3、4、∞边形挡板,时均接触数指标M差别较小,颗粒的混合质量差别较小.
Accounting to the location of core region in the mixing process of binary particles in a rotary retort, flights were set 21 mm away from the center of the rotary retorts to enhance mixing of particles. The mixing enhancement lies on the pushing and cascading of flights. Discrete element method(DEM) was used to simulate the motion and mixing of binary particles in rotary retorts when flights with different shapes were installed. The influence of the flights' shape on the motion and mixing of binary particles in a rotary retort was analyzed. Results show that the averaged terminal angle of unloading increases as the number of flight's sides increases. When the number of flight's sides is 2, only main cascading curtains exist during the operation of rotary retort. When the number flight's sides is 1, 3, 4 or ∞, both main cascading curtains and hanging cascading curtains exist during the operation of rotary retort. Compared with the rotary retort without flights, the core region where small particles are concentrated disappears in rotary retorts with flights, and the distribution of binary particles is more homogeneous. The increase of averaged contact number index is obvious, and the mixing quality gets better when the number of flight's sides increases from 0 to 2. When the number of flight's sides is 2, 3, 4 and ∞, the values of averaged contact number index are approximative, therefore the mixing qualities are approximative.
Accounting to the location of core region in the mixing process of binary particles in a rotary retort, flights were set 21 mm away from the center of the rotary retorts to enhance mixing of particles. The mixing enhancement lies on the pushing and cascading of flights. Discrete element method(DEM) was used to simulate the motion and mixing of binary particles in rotary retorts when flights with different shapes were installed. The influence of the flights' shape on the motion and mixing of binary particles in a rotary retort was analyzed. Results show that the averaged terminal angle of unloading increases as the number of flight's sides increases. When the number of flight's sides is 2, only main cascading curtains exist during the operation of rotary retort. When the number flight's sides is 1, 3, 4 or ∞, both main cascading curtains and hanging cascading curtains exist during the operation of rotary retort. Compared with the rotary retort without flights, the core region where small particles are concentrated disappears in rotary retorts with flights, and the distribution of binary particles is more homogeneous. The increase of averaged contact number index is obvious, and the mixing quality gets better when the number of flight's sides increases from 0 to 2. When the number of flight's sides is 2, 3, 4 and ∞, the values of averaged contact number index are approximative, therefore the mixing qualities are approximative.
引文
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[20]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 Li-dong,LI Shao-hua,ZHU Ming-liang,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.
[21]JIANG M,ZHAO Y,LIU G,et al.Enhancing mixing of particles by baffles in a rotating drum mixer[J].Particuology,2011,9(3):270-278.
[22]钱家麟,尹亮.油页岩:石油的补充能源[M].北京:中国石化出版社,2011:49,319.
[23]王恭,苗宇,孙灵芳,等.回转干馏炉内颗粒停留时间的计算机模拟研究[J].东北电力大学学报,2012,32(3):37-41.WANG Gong,MIAO Yu,SUN Ling-fang,et al.Computer simulation of particles'residence time in rotary dry distillation furnace[J].Journal of Northeast Dianli University,2012,32(3):37-41.
[24]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 Li-dong,WEI Qing-wen,QIN Hong,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.
[2]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 Qing,XIAO Guan-hua,KONG Xiang-zhao,et al.Experimental investigation of solid heat carrier retorting of Huadian oil shale[J].Journal of Northeast Dianli University,2013,33(5):15-21.
[3]高红利,陈友川,赵永志,等.薄滚筒内二元湿颗粒体系混合行为的离散单元模拟研究[J].物理学报,2011,60(12):330-337.GAO Hong-li,CHEN You-chuan,ZHAO Yong-zhi,et al.Simulation of mixing process for size-type binary wet particulate systems in a rotating horizontal drum by discrete element method[J].Acta Physica Sinica,2011,60(12):330-337.
[4]黄德财,冯耀东,解为梅,等.颗粒密度对旋转筒内二元颗粒体系分离的影响[J].物理学报,2012,61(12):372-378.HUANG De-cai,FENG Yao-dong,XIE Wei-mei,et al.Effect of particle density on the segregation of binary granular systems in a rotating drum[J].Acta Physica Sinica,2012,61(12):372-378.
[5]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.
[6]陈辉,肖友刚,赵先琼,等.回转窑内二元颗粒物料的径向混合[J].工程科学学报,2016,38(2):194-199.CHEN Hui,XIAO You-gang,ZHAO Xian-qiong,et al.Transverse mixing of binary solid materials in a rotating kiln[J].Chinese Journal of Engineering,2016,38(2):194-199.
[7]NIELSEN A R,ANIOL R W,LARSEN M B,et al.Mixing large and small particles in a pilot scale rotary kiln[J].Powder Technology,2011,210(3):273-280.
[8]H?HNER D,WIRTZ S,SCHERER V.Experimental and numerical investigation on the influence of particle shape and shape approximation on hopper discharge using the discrete element method[J].Powder Technology,2013,235(2):614-627.
[9]耿凡,徐大勇,袁竹林,等.滚筒干燥器中杆状颗粒混合特性的三维数值模拟[J].东南大学学报:自然科学版,2008,38(1):116-122.GENG Fan,XU Da-yong,YUAN Zhu-lin,et al.Three dimensional numerical simulation of mixing characteristics of slender particles in rotary dryer[J].Journal of Southeast University:Natural Science Edition,2008,38(1):116-122.
[10]李少华,张立栋,张轩,等.回转式干馏炉内影响颗粒混合运动因素的数值分析[J].中国电机工程学报,2011,32(2):32-38.LI Shao-hua,ZHANG Li-dong,ZHANG Xuan,et al.Numerical analysis of particle mixing and movement in rotary retorting[J].Proceedings of the CSEE,2011,32(2):32-38.
[11]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.
[12]MACHADO M V C,NASCIMENTO S M,DUARTE CR,et al.Boundary conditions effects on the particle dynamic flow in a rotary drum with a single flight[J].Powder Technology,2017,311:341-349.
[13]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.
[14]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(2):107-115.
[15]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 Yong-zhi,ZHANG Xian-qi,LIU Yan-lei,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.
[16]CUNDALL P A,STRACK O L.A discrete numerical model for granular assemblies[J].Geotechnique,1979,29(1):47-65.
[17]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 Hui,LIU Yi-lun,ZHAO Xian-qiong,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.
[18]MELLMANN J.The transverse motion of solids in rotating cylinders:forms of motion and transition behavior[J].Powder Technology,2001,118(3):251-270.
[19]张立栋,李连好,程硕,等.颗粒在圆形偏心滚筒内的运动模式[J].化工进展,2015,34(9):3244-3247.ZHANG Li-dong,LI Lian-hao,CHENG Shuo,et al.Motion mode of particles in a circular eccentric drum[J].Chemical Industry and Engineering Progress,2015,34(9):3244-3247.
[20]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 Li-dong,LI Shao-hua,ZHU Ming-liang,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.
[21]JIANG M,ZHAO Y,LIU G,et al.Enhancing mixing of particles by baffles in a rotating drum mixer[J].Particuology,2011,9(3):270-278.
[22]钱家麟,尹亮.油页岩:石油的补充能源[M].北京:中国石化出版社,2011:49,319.
[23]王恭,苗宇,孙灵芳,等.回转干馏炉内颗粒停留时间的计算机模拟研究[J].东北电力大学学报,2012,32(3):37-41.WANG Gong,MIAO Yu,SUN Ling-fang,et al.Computer simulation of particles'residence time in rotary dry distillation furnace[J].Journal of Northeast Dianli University,2012,32(3):37-41.
[24]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 Li-dong,WEI Qing-wen,QIN Hong,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.