回转干馏炉内扰流件的扰动及增混特性
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摘要
采用离散单元法(DEM)模拟了二组元颗粒体系在有扰流件回转干馏炉内的流动和混合。根据涡心区(混合死区)的位置和尺寸在回转干馏炉中分别安装了外接圆半径相等的圆柱、前半圆、后半圆和直板扰流件,研究了扰流件类型对扰流件尾流、颗粒平均速度和大小颗粒混合程度的影响。研究表明:当各扰流件穿过颗粒物料时,其尾流分别经历了左偏尾流、近似对称尾流和右偏尾流。扰流件类型不同,在相同的时刻其尾流的大小存在差异。当回转干馏炉内无扰流件或者有直板扰流件时,颗粒平均速度的波动范围较小,且波动较为不规则。当安装圆柱、前半圆和后半圆扰流件时,平均速度的波动范围较大,且波动规律性较强,每一个波动过程均由一个大波动和一个小波动构成。对于圆柱和前半圆扰流件,小波动位于波动范围的低值区,对于后半圆扰流件,小波动位于波动范围的中值区。对于二组元颗粒系统,当外接圆半径相等时,后半圆扰流件的增混效果最好,但干馏炉耗能最快。圆柱和前半圆扰流件的增混效果次之。直板增混效果最差,但相比于其他绕流件耗能最慢。较大的绕流件终末卸料角更有利于颗粒的增混。
The discrete element method(DEM) was used to simulate the flow and mixing of binary particles in rotary retorts with stirring internals. The cylindrical stirring internals, front semicircular stirring internals, rear semicircular stirring internals and rectangular stirring internals with same radius of circumscribed circle were installed in rotary retorts according to the location and size of core region. The influence of the stirring internals′ shape on averaged velocities and mixing of binary particles was analyzed. Results showed that there were leftward wake flow, approximately symmetrical wake flow and right wake flow existed when the stirring internal traversed the particles. The sizes of wake flows were different at the same moment for different stirring internals. The fluctuation ranges of particles′ averaged velocities were small for the rotary retort without internals or installing rectangular stirring internals. For the rotary retort with cylindrical stirring internals, front semicircular stirring internals or rear semicircular stirring internals, the fluctuation range of particles′ averaged velocities were wide, and the fluctuation was regular. One fluctuating process included one major fluctuation and one small fluctuation. For the cylindrical stirring internals and front semicircular stirring internals, the small fluctuations were in the low value range of the fluctuation range. For the rear semicircular stirring internals, the small fluctuations were in the median value range of the fluctuation range. The mixing enhancement of rectangular stirring internal was worst and that of rear semicircular stirring internal was best, when the radii of circumscribed circles were same, for the binary particle in rotary retorts. The energy consumption of rotary retort with rear semicircular stirring internals was fastest and that of rotary retort with front semicircular stirring internals was slowest. Higher terminal angle of unloading was beneficial for mixing enhancement.
The discrete element method(DEM) was used to simulate the flow and mixing of binary particles in rotary retorts with stirring internals. The cylindrical stirring internals, front semicircular stirring internals, rear semicircular stirring internals and rectangular stirring internals with same radius of circumscribed circle were installed in rotary retorts according to the location and size of core region. The influence of the stirring internals′ shape on averaged velocities and mixing of binary particles was analyzed. Results showed that there were leftward wake flow, approximately symmetrical wake flow and right wake flow existed when the stirring internal traversed the particles. The sizes of wake flows were different at the same moment for different stirring internals. The fluctuation ranges of particles′ averaged velocities were small for the rotary retort without internals or installing rectangular stirring internals. For the rotary retort with cylindrical stirring internals, front semicircular stirring internals or rear semicircular stirring internals, the fluctuation range of particles′ averaged velocities were wide, and the fluctuation was regular. One fluctuating process included one major fluctuation and one small fluctuation. For the cylindrical stirring internals and front semicircular stirring internals, the small fluctuations were in the low value range of the fluctuation range. For the rear semicircular stirring internals, the small fluctuations were in the median value range of the fluctuation range. The mixing enhancement of rectangular stirring internal was worst and that of rear semicircular stirring internal was best, when the radii of circumscribed circles were same, for the binary particle in rotary retorts. The energy consumption of rotary retort with rear semicircular stirring internals was fastest and that of rotary retort with front semicircular stirring internals was slowest. Higher terminal angle of unloading was beneficial for mixing enhancement.
引文
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[24]庞佑霞,郭源君,赵运才.不同条件下Al2O3基陶瓷材料的摩擦磨损性能研究[J].功能材料,2000,31(2):223-224.PANG Y X,GUO Y J,ZHAO Y C.Study of friction and wear behaviors of Al2O3matrix ceramic in various conditions[J].Journal of Functional Materials,2000,31(2):223-224.
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[26]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 H,XIAO Y G,ZHAO X Q,et al.Transverse mixing of binary solid materials in a rotating kiln[J].Chinese Journal of Engineering,2016,38(2):194-199.
[27]YAMAMOTO M,ISHIHARA S,KANO J.Evaluation of particle density effect for mixing behavior in a rotating drum mixer by DEMsimulation[J].Advanced Powder Technology,2015,27(3):864-870.
[2]梁财,陈晓平,赵长遂.加压密相粉煤输送特性及稳定性研究[J].工程热物理学报,2009,30(10):1787-1790.LIANG C,CHEN X P,ZHAO C S.Investigation of flow characteristics and stability of dense-phase pneumatic conveying of pulverized coal at high pressure[J].Journal of Engineering Thermophysics,2009,30(10):1787-1790.
[3]LIANG C,HU JW,LIU HY,et al.Resistance characteristics of pressure letdown in dense-phase pneumatic conveying[J].Journal of Chemical Engineering of Japan,2016,49(6):511-518.
[4]沈杭,杨建红,张认成,等.干粉站用干燥滚筒离散元仿真分析与试验研究[J].机械设计,2016(8):67-71.SHEN H,YANG J H,ZHANG R C,et al.Discrete element simulation analysis and experiment research of rotary dryer in the powder station[J].Journal of Machine Design,2016(8):67-71.
[5]王擎,李建,王智超,等.回转干馏炉内颗粒间传热特性的数值模拟[J].化工学报,2017,68(11):4137-4146.WANG Q,LI J,WANG Z C,et al.Numerical simulation on characteristics of heat transfer between particles in rotary retorting[J].CIESC Journal,2017,68(11):4137-4146.
[6]KHAKHAR D V,ORPE A V,HAJRA S K.Segregation of granular materials in rotating cylinders[J].Physica A Statistical Mechanics&its Applications,2003,318:129-136.
[7]王鹏程,范元钢,王彩玲,等.滚筒混合抄板长度和角度的二维数值模拟仿真[J].兵器装备工程学报,2018,39(4):170-173.WANG P C,FAN Y G,WANG C L,et al.Two dimensional numerical simulations of length and angle of drum mixing plate[J].Journal of Ordnance Equipment Engineering,2018,39(4):170-173.
[8]李利桥,王德福,李超.回转式日粮混合机混合机理分析与性能试验优化[J].农业机械学报,2017,48(8):123-132.LI L Q,WANG D F,LI C.Mixing process and analysis and performance experiment of rotary ration mixer[J].Transactions of the Chinese Society for Agricultural Machinery,2017,48(8):123-132.
[9]李沐沅,凌祥,彭浩,等.板式回转干燥机的颗粒流动传热特性研究[J].压力容器,2016,33(3):21-31.LI M Y,LING X,PENG H,et al.Flow and heat transfer characteristics of materials in the flighted rotary dryer[J].Pressure Vessel Technology,2016,33(3):21-31.
[10]段鸾芳,凌祥.转速对板式回转换热器内颗粒传热性能的影响[J].南京工业大学学报(自科科学版),2017,39(6):99-104.DUAN L F,LING X.Impact of rotating speed on particles heat transfer in plate rotary heat exchanger[J].Journal of Nanjing Tech University(Natural Science Edition),2017,39(6):99-104.
[11]徐颖,吴家正,张亨伟,等.红外滚筒干燥机内颗粒混合的模拟研究[J].节能技术,2018(2):125-129.XU Y,WU J Z,ZHANG H W,et al.Simulation study of particle mixing in an infrared drum dryer[J].Energy Conservation Technology,2018(2):125-129.
[12]SHI D,ABATAN A,VAGAS W,et al.Eliminating segregation in freesurface flows of particles[J].Physical Review Letters,2007,99(14):1-4.
[13]PITON M,HUCHET F,CORRE O L,et al.A coupled thermalgranular model in flights rotary kiln:industrial validation and process design[J].Applied Thermal Engineering,2015,75:1011-1021.
[14]SILVéRIO B C,ARRUDA E B,DUARTE C R,et al.A novel rotary dryer for drying fertilizer:comparison of performance with conventional configurations[J].Powder Technology,2015,270:135-140.
[15]JIANG M Q,ZHAO Y Z,LIU G S,et al.Enhancing mixing of particles by baffles in a rotating drum mixer[J].Particuology,2011,9(3):270-278.
[16]CUNDALL P A,STRACK O L.A discrete numerical model for granular assemblies[J].Geotechnique,1979,29(1):47-65.
[17]CHEN H,XIAO Y G,LIU Y L,et al.2017.Effect of Young,s modulus on DEM results regarding transverse mixing of particles within a rotating drum[J].Powder Technology,2017,318:507-517.
[18]MELLMANN J.The transverse motion of solids in rotating cylindersforms of motion and transition behavior[J].Powder Technology,2001,118(3):251-270.
[19]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.
[20]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.QIAN J L,YIN L.Oil shale:petroleum alternative[M].Beijing:China Petrochemical Press,2011:49,319.
[21]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 G,MIAO Y,SUN L F,et al.Computer simulation of particles,residence time in rotary dry distillation furnace[J].Journal of Northeast Electric Power University,2012,32(3):37-41.
[22]彭瑞东.材料力学性能[M].北京:机械工业出版社,2017:330.PENG R D.Mechanical properties of materials[M].Beijing:China Machine Press,2017:330.
[23]田晓.陶瓷材料摩擦副的摩擦磨损特性研究[D].天津:天津大学,2003.TIAN X.The friction and wear characteristics research of ceramics friction pair[D].Tianjin:Tianjin University,2003.
[24]庞佑霞,郭源君,赵运才.不同条件下Al2O3基陶瓷材料的摩擦磨损性能研究[J].功能材料,2000,31(2):223-224.PANG Y X,GUO Y J,ZHAO Y C.Study of friction and wear behaviors of Al2O3matrix ceramic in various conditions[J].Journal of Functional Materials,2000,31(2):223-224.
[25]李庆阳.玻璃材料的摩擦磨损性能测试及其装置的研制[D].哈尔滨:哈尔滨工业大学,2006.LI Q Y.Friction&wear-based test and development of instrument for glass[D].Harbin:Harbin Institute of Technology,2006.
[26]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 H,XIAO Y G,ZHAO X Q,et al.Transverse mixing of binary solid materials in a rotating kiln[J].Chinese Journal of Engineering,2016,38(2):194-199.
[27]YAMAMOTO M,ISHIHARA S,KANO J.Evaluation of particle density effect for mixing behavior in a rotating drum mixer by DEMsimulation[J].Advanced Powder Technology,2015,27(3):864-870.