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清华大学学报(自然科学版)  2016, Vol. 56 Issue (6): 592-597    DOI: 10.16511/j.cnki.qhdxxb.2016.22.017
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塔式尿素造粒粒径分析
刘孝弟1,2, 朱余乐1, 吕俊复1, 弭艳2, 顾学颖2
1. 清华大学 热能工程系, 北京 100084;
2. 北京航天动力研究所, 北京 100076
Drop diameters during urea prilling
LIU Xiaodi1,2, ZHU Yule1, LV Junfu1, MI Yan2, GU Xueying2
1. Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;
2. Beijing Aerospace Propulsion Institute, Beijing 100076, China
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摘要 塔式造粒是当前生产中小颗粒尿素的主流工艺。根据塔式尿素造粒的物理过程, 分析了形成液滴的液柱的受力情况, 建立了液柱临界长度、 最大液滴直径的计算模型。模型计算与实验数据吻合得较好, 可以用于工程计算。利用该模型, 分析了喷口直径和各种操作条件对液滴直径的影响, 发现喷孔直径和喷孔所在处切向旋转速度对最大液滴直径的影响明显, 而喷孔液流速度影响较弱。塔体通风气流速度在低于1.5 m·s-1时影响较小, 高于1.5 m·s-1时影响显著。在一定范围内, 可以通过调整喷孔直径和喷孔所在处切向旋转速度来提高液滴最大直径, 但是液滴在造粒塔中下落冷却固化过程中可能出现二次分裂, 根据临界Weber数发现塔式尿素造粒的最大直径约是4 mm。
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刘孝弟
朱余乐
吕俊复
弭艳
顾学颖
关键词 塔式造粒尿素固化过程液柱最大液滴直径    
Abstract:Urea is produced in a tower with falling liquid droplets to enhance the evaporation and drying of the urea particles. The physical process has a liquid column feeding an atomizer. This study analyzes the effect of the nozzle diameter, liquid velocity and air flow velocity on the urea maximum drop diameter. A model is developed to predict the critical heights of the liquid column and the maximum drop diameter. The model predictions agree well with the experimental data, indicating its ability to predict the maximum drop diameter. The atomizer nozzle diameter and the tangential velocity at the orifice strongly influence the drop size, while the liquid velocity at the orifice has little impact on the maximum drop diameter. The air flow velocity in the tower also affects the maximum drop diameter when the air flow velocity is greater than 1.5 m·s-1, but the effect is very small for the air flow velocity less than 1.5 m·s-1. Thus, the maximum drop diameter can be increased by increasing the atomizer nozzle diameter and the tangential velocity at the orifice. Secondary breakup will occur with large drops falling in the tower during cooling and solidification. The critical Weber number gives the maximum drop diameter of urea in the tower for granulation processing about 4 mm.
Key wordsgranulation processing tower    urea processing during solidification    liquid column    maximum drop diameter
收稿日期: 2015-05-23      出版日期: 2016-07-01
ZTFLH:  O359  
通讯作者: 吕俊复, 教授, E-mail: lvjf@mail.tsinghua.edu.cn     E-mail: lvjf@mail.tsinghua.edu.cn
引用本文:   
刘孝弟, 朱余乐, 吕俊复, 弭艳, 顾学颖. 塔式尿素造粒粒径分析[J]. 清华大学学报(自然科学版), 2016, 56(6): 592-597.
LIU Xiaodi, ZHU Yule, LV Junfu, MI Yan, GU Xueying. Drop diameters during urea prilling. Journal of Tsinghua University(Science and Technology), 2016, 56(6): 592-597.
链接本文:  
http://jst.tsinghuajournals.com/CN/10.16511/j.cnki.qhdxxb.2016.22.017  或          http://jst.tsinghuajournals.com/CN/Y2016/V56/I6/592
  图1 尿素液流出喷头的速度示意图
  图2 尿素液柱受力情况分析
  图3 模型计算结果与实验测量结果的比较
  图4 喷孔处切线速度和塔内通风上升速度对最大液柱长度和液滴直径的影响 (d=1.5mm,v=3.2m·s-1)
  图5 喷孔出口速度对最大液柱长度和液滴直径的影响(v=0.6m·s-1,v=5m·s-1)
  图6 喷孔直径对最大液柱长度和液滴直径的影响(v=3.2m·s-1,v=0.6m·ss-1,v=5m·ss-1)
  图7 尿素颗粒的粒度分布实验结果与模型计算结果对比
[1] Lefebver A H. Atomization and Spray [M]. New York, NY, USA: Hemisphere Publishing Corporation, 1989.
[2] Lefebver A H. Gas Turbine Combustion [M]. New York, NY, USA: Hemisphere Publishing Corporation, 1983.
[3] 中国寰球化学工程公司. 氮肥工艺手册: 尿素 [M]. 北京: 化学工业出版社, 1988.China Huanqiu Contracting & Engineering Corp (HQC). Manual of Nitrogen Fertilizer Processing: Urea [M]. Beijing: Chemical Industry Press, 1988. (in Chinese)
[4] 孔珑. 工程流体力学 [M]. 北京: 中国电力出版社, 2007.KONG Long. Engineering Fluid Mechanics [M]. Beijing: China Electric Power Press, 2007. (in Chinese)
[5] Chandrasehar S. Hydrodynamic and Hydromagnetic Stability [M]. Oxford, UK: Oxford University Press, 1961.
[6] Rizk N K, Lefebvre A H. The influence of liquid film thickness on air blast atomization [J]. ASME Journal of Engineering for Power, 1980, 102: 706-710.
[7] Varga C M, Lasheras J C, Hopfinger E J. Initial breakup of a small-diameter liquid jet by a high-speed gas stream [J]. Journal of Fluid Mechanics, 2003, 497: 405-434.
[8] Semiao V, Andrade P, Carvatho M D G. Spray characterization: Numerical prediction of SMD and droplet size distribution [J]. Fuel, 1996, 75(15): 1707-1714.
[9] 王振国, 吴晋湘, 鄢小清, 等. 气液同轴离心式喷嘴喷雾流场数值模拟 [J]. 推进技术, 1996,17(3): 43-49.WANG Zhenguo, WU Jinxiang, YAN Xiaoqing, et al. Numerical simulation of spray flow processes in coaxial swirling injector [J]. Journal of Propulsion Technology, 1996, 17(3): 43-49. (in Chinese)
[10] Li J, Renardy Y Y, Renardy M. Numerical simulation of breakup of a viscous drop in simple shear flow through a volume-of-fluid method [J]. Physics of Fluids, 2000, 12(2): 269-282.
[11] 解茂昭.燃油喷雾场结构与雾化机理 [J].力学与实践, 1990, 12(4): 9-15.XIE Maozhao. Spray field structure of fuel and atomization mechanism [J]. Mechanics and Engineering, 1990, 12(4): 9-15. (in Chinese)
[12] Pilch M, Erdman C A. Use of break-up time data and velocity history data to predict the maximum size of stable fragments for acceleration-induced break-up of a liquid drop [J]. International Journal of Multiphase Flow, 1987, 13(6): 741-757.
[13] 甘晓华. 航空燃气轮机燃油喷嘴技术 [M]. 北京: 国防工业出版社, 2006.GAN Xiaohua. Technology of Fuel Nozzle in Aviation Gas Turbine [M]. Beijing: National Defense Industry Press, 2006. (in Chinese)
[14] 岑可法, 姚强, 曹欣玉, 等. 煤浆燃烧、 流动、 传热和气化的理论与应用技术 [M].杭州: 浙江大学出版社, 1995.CEN Kefa, YAO Qiang, CAO Xinyu, et al. Theory and Application Technology of Combustion, Flow, Heat Transfer and Gasification of Coal Slurry [M]. Hangzhou: Zhejiang University Press, 1995. (in Chinese)
[15] Scweitzer P H. Mechanisms of disintegration of liquid jets [J]. Journal of Applied Physics, 1937, 8(8): 513-521.
[16] Hinze J O. Fundamentals of the hydrodynamic mechanism of splitting in dispersion process [J]. AIChE Journal, 1955, 1(3): 289-295.
[17] Giffen T, Muraszew A. The Atomization of Liquid Fuels [M]. New York, NY, USA: John Wiley & Sons, 1953.
[18] 刘孝弟, 褚晓斌, 蒋刚. 尿素造粒机理研究 [J]. 化肥工业, 2015, 42(3): 21-28.LIU Xiaodi, CHU Xiaobin, JIANG Gang. Study of mechanism of urea granulation [J]. Chemical Fertilizer Industry, 2015, 42(3): 21-28. (in Chinese)
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