潜水搅拌器安装角度对盐泥水洗搅拌效果的影响
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摘要
针对传统搅拌桨型无法满足盐泥水洗搅拌的问题,提出了双潜水搅拌式水洗设备,借助Fluent17.0软件,采用MRF法、标准k-ε湍流模型,对该水洗设备中盐泥-水洗剂混合过程进行数值模拟,以流速场、混合时间、单位体积混合能、盐泥体积分数标准差、湍动能以及湍动能耗散率为指标,研究了搅拌叶轮转速为480 r/min时,水洗设备内双潜水搅拌器以不同安装角度下的混合特性,并通过实验验证模拟仿真的有效性。研究结果表明:各安装角度下的搅拌流速场不具对称性,近潜水搅拌器的流体区域流动较为紊乱,安装角度α为20°时,整个流体域内低流速区占比小,远离搅拌器的下游处流速较高且分布均匀,两相混合时间和混合时间数最小,混合均匀度最佳,适用于快速式搅拌模式;α为40°时,湍动能耗散率最小,单位体积混合能最小,可达到最佳的节能效果,适用于持久式搅拌模式。实验结果表明数值模拟结论有效,可为盐泥的高效水洗处理提供一定的参考。
Aiming at the problem that the traditional mixing paddle cannot meet the requirements of salt water washing and stirring, a double submersible stirring-type washing equipment is proposed. With the Fluent17.0, the MRF method and standard k-ε turbulence model are used to mix the salt mud-water lotion in the washing equipment. The numerical simulation was conducted in the process. The velocity field, mixing time, mixing energy per unit volume, standard deviation of salt mud volume fraction, turbulent kinetic energy and the turbulent energy dissipation rate were used to study the stirring speed of the stirring impeller at 480 r/min. The mixing characteristics of the double submersible mixer at different installation angles were studied and the experimental results verified the effectiveness of the simulation. It is shown that the agitation flow field under each installation angle is not symmetrical, and the fluid flow in the submersible agitator is relatively disorderly. When the installation angle is 20°, the proportion of low flow area in the whole fluid domain is small; the flow rate is relatively high and evenly distributed away from the downstream of the agitator; the mixing time and dimensionless mixing time of the two phases are the shortest; and the mixing uniformity is the best in the fast mixing mode. When the angle is 40°, the turbulent energy dissipation rate and the mixing energy per unit volume are the smallest, which can achieve the best energy saving, suitable for persistent stirring mode. The experimental result shows that the numerical simulation conclusion is effective and can provide reference for the efficient washing treatment of salt mud.
Aiming at the problem that the traditional mixing paddle cannot meet the requirements of salt water washing and stirring, a double submersible stirring-type washing equipment is proposed. With the Fluent17.0, the MRF method and standard k-ε turbulence model are used to mix the salt mud-water lotion in the washing equipment. The numerical simulation was conducted in the process. The velocity field, mixing time, mixing energy per unit volume, standard deviation of salt mud volume fraction, turbulent kinetic energy and the turbulent energy dissipation rate were used to study the stirring speed of the stirring impeller at 480 r/min. The mixing characteristics of the double submersible mixer at different installation angles were studied and the experimental results verified the effectiveness of the simulation. It is shown that the agitation flow field under each installation angle is not symmetrical, and the fluid flow in the submersible agitator is relatively disorderly. When the installation angle is 20°, the proportion of low flow area in the whole fluid domain is small; the flow rate is relatively high and evenly distributed away from the downstream of the agitator; the mixing time and dimensionless mixing time of the two phases are the shortest; and the mixing uniformity is the best in the fast mixing mode. When the angle is 40°, the turbulent energy dissipation rate and the mixing energy per unit volume are the smallest, which can achieve the best energy saving, suitable for persistent stirring mode. The experimental result shows that the numerical simulation conclusion is effective and can provide reference for the efficient washing treatment of salt mud.
引文
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[2] DAPELO D,ALBERINI F,BRIDGEMAN J.Euler-Lagrange CFD modelling of unconfined gas mixing in anaerobic digestion [J].Water Research,2015,85:497-511.
[3] LANE G L,SCHWARZ M P,EVANS G M.Comparison of CFD methods for modelling of stirred tanks [C]//10th European Conference on Mixing.Delft,Holland:Delft University of Technology,2000:273-280.
[4] 张晓宁,赵静野,王文海.潜水搅拌器安装角度对搅拌效果的影响 [J].北京建筑大学学报,2014(4):48-51.ZHANG Xiaoning,ZHAO Jingye,WANG Wenhai.Influence of installation angle of submersible mixer on stirring effect [J].Journal of Beijing Jianzhu University,2014(4):48-51.
[5] 施卫东,田飞,曹卫东,等.不同池形中推流搅拌器功率消耗的数值模拟 [J].排灌机械工程学报,2009,27(3):140-144.SHI Weidong,TIAN Fei,CAO Weidong,et al.Numerical simulation of power consumption of pusher agitator in different pool shapes [J].Journal of Drainage and Irrigation Machinery Engineering,2009,27(3):140-144.
[6] WRAY J,ALPERS D.Large blade submersible mixers increase efficiency,save money [EB/OL].[2018-11-23].http://www.pumpscout.com/articles-expertadvice/large-blade-submersible-mixers-increase-efficiency-savemoney-aid635.html.
[7] 韩占忠,王敬,兰小平.FLUENT流体工程仿真计算实例与应用 [M].北京:北京理工大学出版社,2004:14-15.
[8] 朱桂华,柳颖娇,徐洪威,等.高黏度污泥螺带螺杆搅拌混合特性的数值模拟 [J].安全与环境学报,2018,18(3):1121-1126.ZHU Guihua,LIU Yingjiao,XU Hongwei,et al.Numerical simulation of mixing characteristics of high-viscosity sludge ribbon screw agitation [J].Journal of Safety and Environment,2018,18(3):1121-1126.
[9] 江帆,黄鹏.Fluent高级应用与实例分析 [M].北京:清华大学出版社,2008:77-85.
[10] KASAT G R,KHOPKAR A R,RANADE V V,et al.CFD simulation of liquid-phase mixing in solid-liquid stirred reactor [J].Chemical Engineering Science,2008,63(15):3877-3885.
[11] 朱桂华,朱天宏,洪小波,等.关于污泥搅拌器均匀度混合优化仿真 [J].计算机仿真,2017,34(12):411-414.ZHU Guihua,ZHU Tianhong,HONG Xiaobo,et al.Simulation of uniformity mixing of sludge agitator [J].Computer Simulation,2017,34(12):411-414.
[12] 梁瑛娜,高殿荣,拜亮.双层桨搅拌槽内层流流场与混合时间的数值模拟 [J].机械工程学报,2015,51(16):185-195.LIANG Yingna,GAO Dianrong,BAI Liang.Numerical simulation of laminar flow field and mixing time in a double-layer paddle stirred tank [J].Journal of Mechanical Engineering,2015,51(16):185-195.
[13] WANG F,MAO Z S,WANG Y,et al.Measurement of phase holdups in liquid-liquid-solid three-phase stirred tanks and CFD simulation [J].Chemical Engineering Science,2006,61(22):7535-7550.
[14] KERDOUSS F,BANNARI A,PROULX P,et al.Two-phase mass transfer coefficient prediction in stirred vessel with a CFD model [J].Computers & Chemical Engineering,2008,32(8):1943-1955.
[15] 贺靖峰,赵跃民,骆振福,等.基于Euler-Euler模型的空气重介质流化床密度分布特性 [J].煤炭学报,2013,38(7):1277-1282.HE Jingfeng,ZHAO Yuemin,LUO Zhenfu,et al.Density distribution characteristics of air heavy medium fluidized bed based on Euler-Eulerian model [J].Journal of Coal,2013,38(7):1277-1282.
[16] 田飞,施卫东.潜水搅拌机理论、设计及工程应用 [M].北京:科学出版社,2016:74-79.
[17] 段晓霞,程荡,程景才,等.搅拌槽反应器内宏观和微观混合及过程强化 [J].化学反应工程与工艺,2013,29(3):238-246.DUAN Xiaoxia,CHENG Dang,CHENG Jingcai,et al.Macroscopic and microscopic mixing and process strengthening in a stirred tank reactor [J].Chemical Reaction Engineering and Technology,2013,29(3):238-246.
[18] 栾德玉,周慎杰,陈颂英.错位六弯叶搅拌罐内假塑性流体的混合特性 [J].高校化学工程学报,2012,26(5):787-792.LUAN Deyu,ZHOU Shenjie,CHEN Songying.Mixing characteristics of pseudoplastic fluid in a misaligned six-bend mixing tank [J].Journal of Chemical Engineering of Chinese Universities,2012,26(5):787-792.
[19] 张建伟,程龙,冯颖,等.水平三向撞击流反应(混合)器内湍流数值模拟研究 [J].沈阳化工大学学报,2015,29(3):263-267.ZHANG Jianwei,CHENG Long,FENG Ying,et al.Numerical simulation of turbulent flow in a horizontal three-way impinging stream reaction (mixer) [J].Journal of Shenyang University of Chemical Technology,2015,29(3):263-267.
[20] 张国娟.搅拌槽内混合过程的数值模拟 [D].北京:北京化工大学,2004:20-23.