Measurement of flow characteristics of settler in mixer-settler

doi:10.11949/0438-1157.20190534

Abstract

Abstract:

The mixer-settler is widely used in the rare earth solvent extraction process, and the phase separation process in the settler is very important. The velocity flow field in settler was measured by particle image velocimetry(PIV). Different operational parameters were estimated to study the flow characteristics in settler. These parameters were impeller speed in mixer, volume fraction of organic phase, and different baffle designs. The magnitude of velocity vector in settler had positive correlation with the impeller speed, which could be considered as energy input. The volume fraction of organic phase had little influence on the flow pattern. But it changed the flow direction of the aqueous phase, and strengthened the turbulence in settler. Adding baffle is a promising method to improve the performance of settling. The impact of number and position of baffles in settler on flow structure were surveyed and analyzed. Moreover, the entrainment in aqueous outlet was obtained by conductivity meter, giving clues for comparison and optimization of settler.

Key words: settler, flow characteristics, particle image velocimetry, baffle, entrainment

摘要：

混合澄清槽被广泛应用于稀土溶剂萃取过程，在澄清室内的分相过程是非常重要的环节。采用粒子图像测速技术对澄清室内速度流场进行了测量，比较了不同操作参数下，主要包括混合室搅拌转速、油水两相体积分数以及不同挡板设计对澄清室内流场结构的影响。搅拌转速作为能耗输入，与澄清室内速度矢量大小呈正相关关系；增加油相后，对澄清室内流场结构影响不大，但会使得流动方向发生变化，且使得湍动增加。挡板设计是强化澄清室分相性能的重要途径，对不同挡板组合的澄清室设计进行了测量分析，对挡板形状（Ⅴ形与矩形）、挡板数量与安置位置的影响进行了比较，并采用电导率仪获得澄清室水相出口处溶解性总固体浓度，表征油相夹带情况，对不同挡板设计进行了比较和优化。

关键词: 澄清槽, 流动特性, 粒子图像测速技术, 挡板, 油相夹带

CLC Number:

TQ 028.8

Sishi YE, Qiao TANG, Yundong WANG. Measurement of flow characteristics of settler in mixer-settler[J]. CIESC Journal, 2020, 71(2): 535-543.

叶思施, 唐巧, 王运东. 混合澄清槽澄清室内流场特性测量[J]. 化工学报, 2020, 71(2): 535-543.

Figures/Tables 11

Fig.1 Experimental structure of mixer-settler

Fig.2 Real picture of particle image velocimetry

Fig.3 Schematic diagram of particle image velocity

Table 1 Properties of deionized water and sulfonated kerosene

流体	密度/(kg/m³)	黏度/(kg/(m·s))
去离子水	998.2	0.001
磺化煤油	780	0.0024

Fig.4 Velocity vector in settler for different rotating speeds

Fig.5 Velocity vector in settler for different organic volume fraction

Fig.6 Baffle design in settler

Table 2 Parameters and location of baffles

结构参数	V形挡板	矩形挡板
长度 x/mm	5	5
宽度y/mm	200	200
高度z/mm	~170	100
挡板角度/(°)	45	—

Fig.7 Velocity vector diagrams in settler with baffle for different organic volume fraction

Fig.8 Velocity vector diagrams in settler with different baffle designs

Fig.9 Organic entrainment in aqueous outlet of settler with different baffle designs

References 35

1	徐光宪, 袁承业. 稀土的溶剂萃取[M]. 北京: 科学出版社, 1987.
	Xu G X, Yuan C Y. Solvent Extraction of Rare Earths[M]. Beijing: Science Press, 1987.
2	赵文静, 王东杰. 当今世界稀土分离技术的发展与中国稀土萃取工业进程[J]. 稀土信息, 2015, (3): 28-29.
	Zhao W J, Wang D J. The development of rare earth separation technology in the world and China s rare earth extraction industry process[J]. Rare Earth Information, 2015, (3): 28-29.
3	焦芸芬, 何小林, 廖春发, 等. 近十年来重稀土元素分离与提纯技术研究进展[J]. 稀土, 2013, 34(4): 74-79.
	Jiao Y F, He X L, Liao C F, et al. Progress of research on separation and purification of heavy rare earth elements in recent decade[J]. Chinese Rare Earth, 2013, 34(4): 74-79.
4	邓佐国, 徐廷华. 离子型稀土萃取分离工艺技术现状及发展方向[J]. 有色金属科学与工程, 2012, 3(4): 20-23.
	Deng Z G, Xu T H. The current status and development tendency of ionic rare earth exaction separation process[J].Nonferrous Metals Science and Engineering, 2012, 3(4): 20-23.
5	丁凝, 刘建明, 孙峰. 膜分离技术在稀土废水处理中的应用[J]. 能源研究与管理, 2014, (2): 11-13.
	Ding N, Liu J M, Sun F. Application of membrane separation technique in rare-earth waste water treatment[J]. Energy Research and Mangement, 2014, (2): 11-13.
6	侯海龙. 膜分散萃取分离轻稀土元素[D]. 北京: 北京理工大学, 2015.
	Hou H L. Study on the solvent extraction and separation of light rare earth elements by using membrane dispersion micro-extractor[D]. Beijing: Beijing Institute of Technology, 2015.
7	黄国强, 张峰. 轻稀土分离研究进展[J]. 现代化工, 2015, 35(10): 12-15.
	Huang G Q, Zhang F. Progress of separation of light rare earth elements[J]. Modern Chemical Industry, 2015, 35(10): 12-15.
8	王月, 靖宇, 王运东, 等. 微胶囊固定化P507萃取Sm³⁺的性能研究与优化[J]. 化工学报, 2016, 67(2): 614-622.
	Wang Y, Jing Y, Wang Y D, et al. Performance and optimization of Sm³⁺ extraction by microcapsules containing P507[J]. CIESC Journal, 2016, 67(2): 614-622.
9	刘晶, 王运东. 皂化P507-HCl-煤油体系萃取镨钕[J]. 化工学报, 2014, 65(1): 264-270.
	Liu J, Wang Y D. Extraction of praseodymium (Ⅲ) and neodymium(Ⅲ) in saponified P507-HCl-kerosene system[J]. CIESC Journal, 2014, 65(1): 264-270.
10	Zou Y, Ye S S, Wang Y D, et al. CFD simulation and PIV measurement of liquid-liquid two-phase flow in pump-mix mixer[J]. J. Taiwan Inst. Chem. Eng., 2015, 20(46): 1-11.
11	邹洋. 混合澄清槽性能强化研究[D]. 北京: 清华大学, 2014.
	Zou Y. Process intensification of mixer settler[D]. Beijing: Tsinghua University, 2014.
12	张艳艳, 巩轲, 何淑芳, 等. 激光多普勒测速技术进展[J]. 激光与红外, 2010, 40(11): 1157-1162.
	Zhang Y Y, Gong K, He S F, et al. Progress in laser Doppler velocity measurement techniques[J]. Laser & Infrared, 2010, 40(11): 1157-1162.
13	周国忠. 搅拌槽内流动与混合过程的实验研究及数值模拟[D]. 北京: 北京化工大学, 2002.
	Zhou G Z. Experimental and numerical study on fluid dynamics and mixing process in stirred tank[D]. Beijing: Beijing University of Chemical Technology, 2002.
14	Das M D, Hrymak A N, Baird M H I. Laminar liquid-liquid dispersion in the SMX static mixer[J]. Chemical Engineering Science, 2013, 101(14): 329-344.
15	许联锋, 陈刚, 李建中, 等. 粒子图像测速技术研究进展[J]. 力学进展, 2003, 33(4): 533-540.
	Xu L F, Chen G, Li J Z, et al. Research progress of particle image velocimetry[J]. Advances in Mechanics, 2003, 33(4): 533-540.
16	Salem A I, Okoth G, Thoming J. An approach to improve the separation of solid-liquid suspensions in inclined plate settlers: CFD simulation and experimental validation[J]. Water Res., 2011, 45: 3541-3549.
17	Mohanarangam K, Yang W, Barnard K R, et al. Flow mapping of full scale solvent extraction settlers using pulsed Doppler UVP technique[J]. Chem. Eng. Sci., 2013, 104: 925-933.
18	Alonso M M, Navarro M A, Castro F D, et al. Improvement of a system for catchment, pretreatment, and treatment of runoff water using PIV tests and numerical simulation[J]. J. Irrig. Drainage Eng., 2014, 140(8): 04014028.
19	Lane G L, Mohanarangam K, Yang W, et al. Flow pattern assessment and design optimization for an industrial solvent extraction settler through in situ measurements and CFD modelling[J]. Chem. Eng. Res. Des., 2016, 109: 200-214.
20	徐培昇. 大流比全逆流混合澄清槽结构参数的试验研究[J]. 核科学与工程, 2017, 37(3): 501-508.
	Xu P S. The hydraulic experiment research of full countercurrent mixer settler with large ratio[J]. Nuclear Science and Engineering, 2017, 37(3): 501-508.
21	Sadeghi R, Mohebbi A, Sarrafi A, et al. CFD simulation and optimization of the settler of an industrial copper solvent extraction plant: a case study[J]. Hydrometallurgy, 2011, 106(3/4): 148-158.
22	Rajeswari S, Suhasini B, Antony M P, et al. Phase separation time measurement using optical method for solvent characterization[J]. Sep. Sci. Technol., 2012, 47: 1498-1506.
23	Wang S C, Zhang T A, Zhao Q Y, et al. Experimental study on aqueous phase entrainment in a mixer-settler with double stirring mode[J]. China Petroleum Processing and Petrochemical Technology, 2013, 15(2): 59-62.
24	王淑婵, 张廷安, 赵秋月, 等. 新型混合澄清槽的澄清性能[J]. 东北大学学报(自然科学版), 2014, 35(4): 548-568.
	Wang S C, Zhang T A, Zhao Q Y, et al. Settling performance of new type mixer-settler[J]. Journal of Northeastern University (Natural Science), 2014, 35(4): 548-568.
25	肖传绪, 黄焜, 刘会洲. 混合澄清萃取槽内水油两相相比变化对其操作性能的影响[J]. 过程工程学报, 2017, 17(5): 885-892.
	Xiao C X, Huang K, Liu H Z. Effect of change in aqueous-to-oil phase ratio on the performance of mixer-settler in extraction processes[J]. The Chinese Journal of Process Engineering, 2017, 17(5): 885-892.
26	Barega E, Zondervan E, de Haan A. Entrainment reduction in a static-mixer settler setup by electric field enhanced coalescence[J]. Separation Science and Technology, 2014, 49(2): 186-196.
27	Eow J S, Ghadiri M. The behaviour of a liquid-liquid interface and drop-interface coalescence under the influence of an electric field[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003, 215(1/2/3): 101-123.
28	苏立民. 混合-澄清萃取器研究及设计的新进展[J]. 化工冶金, 1980, 1(3): 124-145.
	Su L M. New progress in research and design of mixer-settler[J]. Chemical Metallurgy, 1980, 1(3): 124-145.
29	李洲, 杨志华, 谭世语, 等. 混合澄清槽澄清性能的改进研究(Ⅰ): 填料的助澄清性能[J]. 稀有金属, 1986, 10(5): 354-361.
	Li Z, Yang Z H, Tang S Y, et al. Study on the improvement of clarification performance of mixed settler (Ⅰ): Assisted clarification performance of packing[J]. Chinese Journal of Rare Metals, 1986, 10(5): 354-361.
30	Lewis I E, 韩凤文, 魏士良. 降低夹带损失和减少投资费用的混合澄清器设计[J]. 湿法冶金, 1983, 2(2): 69-70.
	Lewis I E, Han F W, Wei S L. Hybrid clarifier design to reduce entrainment loss and investment cost[J]. Hydrometallurgy of China, 1983, 2(2): 69-70.
31	Lewis I E, 韩凤文, 魏士良. 降低夹带损失和减少投资费用的混合澄清器设计(续) [J]. 湿法冶金, 1983, 2(3): 71-74.
	Lewis I E, Han F W, Wei S L. Hybrid clarifier design to reduce entrainment loss and investment cost (continued)[J]. Hydrometallurgy of China, 1983, 2(3): 71-74.
32	苏立民, 全学军, 林平. 用助澄清挡板增进液液分相的研究[J]. 化工冶金, 1988, 9(2): 44-50.
	Su L M, Quan X J, Lin P. Study on improving liquid-liquid phase separation with auxiliary clarifying baffle[J].Chemical Metallurgy, 1988, 9(2): 44-50.
33	付子忠. 多层澄清萃取器的应用——铀纯化的半工业试验[J]. 铀矿冶, 1992, 11(3): 38-40.
	Fu Z Z. Application of multilayer clarifier extractor — semi-industrial test of uranium purification[J]. Uranium Mining and Metallurgy, 1992, 11(3): 38-40.
34	叶思施, 唐巧, 乔军帅, 等. P507-煤油体系物性测量及其在澄清槽内的CFD模拟[J]. 化工学报, 2016, 67(2): 458-468.
	Ye S S, Tang Q, Qiao J S, et al. Physical properties measurements and CFD simulations in settler of different P507-kerosene systems[J]. CIESC Journal, 2016, 67(2): 458-468.
35	Ye S S, Tang Q, Wang Y D, et al. PIV measurement and CFD simulation of liquid-liquid flow of a settler in rare earths solvent extraction mixer-settler[J]. Int. J. Heat Fluid Flow, 2016, 62: 568-576.

[1]	Chao NIU, Shengqiang SHEN, Yan YANG, Bonian PAN, Yiqiao LI. Flow process calculation and performance analysis of methane BOG ejector [J]. CIESC Journal, 2023, 74(7): 2858-2868.
[2]	Bimao ZHOU, Shisen XU, Xiaoxiao WANG, Gang LIU, Xiaoyu LI, Yongqiang REN, Houzhang TAN. Effect of burner bias angle on distribution characteristics of gasifier slag layer [J]. CIESC Journal, 2023, 74(5): 1939-1949.
[3]	Tienan LI, Bidan ZHAO, Peng ZHAO, Yongmin ZHANG, Junwu WANG. CFD-DEM simulation of the force acting on immersed baffles during the start-up stage of a gas-solid fluidized bed [J]. CIESC Journal, 2022, 73(6): 2649-2661.
[4]	Jianwei ZHANG, Baoshuai LI, Xin DONG, Ying FENG. Numerical simulation of power-law fluid flow characteristics in impinging stream reactor [J]. CIESC Journal, 2022, 73(11): 4917-4927.
[5]	WANG Jiaxing, ZHAO Jiarui, LI Site, FU Yuan, LIU Fengjie, WEI Chang. Influence of different discharge valve flow characteristics on ejection process [J]. CIESC Journal, 2021, 72(S1): 318-325.
[6]	Chenyue LIU, Tong ZHENG, Yuanbo LIU, Rongfu WEN, Kai CHEN, Xuehu MA. Shell side high efficiency and low resistance performance of heat exchanger with bionic structures [J]. CIESC Journal, 2021, 72(9): 4511-4522.
[7]	LI Wenjin, ZHOU Yongjun, YUAN Mingyue, HE Hua, SUN Jianping. Comparative study of the flow characteristics in several frame-type impeller stirred tanks [J]. CIESC Journal, 2021, 72(4): 1998-2005.
[8]	BIE Haiyan, HUANG Chen, AN Weizhong, LI Yulong, LIN Zixin. Numerical simulation of internal flow characteristics of feedback fluidic oscillator [J]. CIESC Journal, 2021, 72(3): 1504-1511.
[9]	Haifeng LU, Hu RUAN, Jiakun CAO, Xiaolei GUO, Haifeng LIU, Chongshuo YUAN. Analysis of the gas-solid fluid dynamic interaction on fine powder discharge [J]. CIESC Journal, 2021, 72(11): 5533-5542.
[10]	Shuxing ZHENG, Zilong ZHU, Yaping CHEN, Jiafeng WU. Universal calculation model of mass center equivalent rectangle for helical baffle heat exchangers [J]. CIESC Journal, 2020, 71(7): 3050-3059.
[11]	Zuohua LIU, Chuang WANG, Wei SUN, Changyuan TAO, Yundong WANG. Chaotic mixing and droplet dispersion characteristics of liquid - liquid with elastic combined impeller [J]. CIESC Journal, 2020, 71(10): 4611-4620.
[12]	Simin WANG, Lijuan SUN, Chen SONG, Zaoxiao ZHANG, Jian WEN. Multi-objective optimization on shell-side performance of rod-baffle heat exchangers with twisted oval tubes [J]. CIESC Journal, 2019, 70(9): 3353-3362.
[13]	Lei ZHOU, Wu ZHOU, Yan ang GUO, Xiaoshu CAI. Experimental studies on coherent structures in jet entrainment boundary layers [J]. CIESC Journal, 2019, 70(7): 2520-2527.
[14]	Yuxin WU, Qiao TANG, Jiyizhe ZHANG, Yundong WANG. Study on mixing and settling characteristics in mixer-settler [J]. CIESC Journal, 2019, 70(10): 3932-3940.
[15]	WU Jiandong, LIU Qiao, WANG Hao. Experimental investigation of fine particle precipitation in rectangular duct with staggered baffles [J]. CIESC Journal, 2018, 69(S1): 15-19.