Motion and distribution of gas-solid two-phase flow in elbow with two-phase deflector

doi:10.11949/j.issn.0438-1157.20151633

Abstract

Abstract:

In view of the problem that gas-solid two-phase flow is not evenly distributed in the elbow of the entrance of flue gas pollutants removal system in the coal-fired power plant,a new two-phase deflector structure was put forward. CFD numerical simulation was employed to analyze the uniform effect of two-phase deflector and conventional deflector. The effect of the two-phase deflector on the distribution law of flow velocity and particle mass, and the effect of the plate shape and the plate angle on the uniform effect of two-phase deflector were simultaneously studied. Finally, the optimum structure of the two-phase deflector was obtained by the Design-Expert response surface method and CFD. The optimal structure was applied to the industrial test and the final result of the calculation and industrial test data were compared. The results showed that it is better to install two-phase deflector than deflector or delta wing baffle in the elbow because of the more uniform distribution and lower pressure drop. The flow velocity distribution and the particle mass concentration distribution changed gradually with the increase of the angle between the plates and the pressure drop of the elbow increased with the angle between the plates too. The optimum structure was the two-phase deflector with the angle of 75.49°and straight plate type. The comparison between the simulation and field measurements showed good agreement. The numerical simulation method proposed by this paper can be used to calculate gas-solid flows in the ESP inlet elbow with complex internal structure in detail.

Key words: two-phase flow, elbow, numerical simulation, homogenization, distribution

摘要：

针对燃煤电厂烟气污染物脱除设备入口弯管内气固两相分布不均的问题提出一种新型两相均流板,采用CFD数值模拟首先对比分析了安装两相均流板与常规导流装置的均流效果,之后详细研究了新型两相均流板对弯管水平出口管道中气流速度、颗粒质量分布规律的影响以及板型及板间夹角对两相均流板均流效果的影响,并结合Design-Expert响应面法获得两相均流板的最优结构,将最优结构应用于工业性实验中,最后将计算结果与工业性实验数据进行了比较。结果表明:弯管内安装两相均流板较安装导流板/三角翼挡板气固两相均流效果更优,既可以使气固两相均匀分布又可以有效降低系统的压阻;随板间夹角的增大,管内的气流速度分布以及颗粒的质量浓度分布呈阶段性变化,而管内的压降则随板间夹角增大而增大;最佳两相均流板结构为夹角为75.49°的直板型两相均流板。模拟与实验结果吻合较好,利用提出的数值模拟方法可以详细真实地模拟计算大型及具有复杂内部结构的除尘器入口弯管中气固两相流动。

关键词: 两相流, 弯道, 数值模拟, 均化, 分布

CLC Number:

TQ051.1

PAN Xiaohui, MA Chunyuan, CUI Lin. Motion and distribution of gas-solid two-phase flow in elbow with two-phase deflector[J]. CIESC Journal, 2016, 67(6): 2308-2317.

潘晓慧, 马春元, 崔琳. 两相均流板对弯管中气固两相运动分布特征的影响[J]. 化工学报, 2016, 67(6): 2308-2317.

References 22

[1]	XU C, LIANG C, ZHOU B, et al. HHT analysis of electrostatic fluctuation signals in dense-phase pneumatic conveying of pulverized coal at high pressure [J]. Chemical Engineering Science, 2010, 65(4): 1334-1344.
[2]	JASSIM E, BENSON S A, BOWMAN F M, et al. The influence of fragmentation on the behavior of pyrite particles during pulverized coal combustion [J]. Fuel Processing Technology, 2011, 92(5): 970-976.
[3]	CHINNAYYA A, CHTAB A, SHAO J Q, et al. Characterization of pneumatic transportation of pulverised coal in a horizontal pipeline through measurement and computational modelling [J]. Fuel, 2009, 88(12): 2348-2356.
[4]	DRITSELIS C D, VLACHOS N S. Large eddy simulation of gas-particle turbulent channel flow with momentum exchange between the phases [J]. International Journal of Multiphase Flow, 2011, 37(7): 1-16.
[5]	AKILLI H, LEVY E K, SAHIN B. Gas-solid flow behavior in a horizontal pipe after a 90° vertical-to-horizontal elbow [J]. Powder Technology, 2001, 116(1): 43-52.
[6]	YILMAZ A, LEVY E K. Formation and dispersion of ropes in pneumatic conveying [J]. Powder Technology, 2001, 114(1): 168-185.
[7]	蔡杰, 钟文琪, 袁竹林. 提升管内细长颗粒流化运动的气固多向耦合模型的构建 [J]. 化工学报, 2015, 66(11): 4342-4350.DOI: 10.11949/j.issn.0438-1157.20150445. CAI J, ZHONG W Q, YUAN Z L. Modeling of gas-solid multi-way coupling of fluidization of slender particles in riser [J]. CIESC Journal, 2015, 66(11): 4342-4350.
[8]	古新, 朱培纳, 刘敏珊, 等. 变截面导流筒换热器入口流场均化性能数值仿真 [J]. 化工学报, 2012, 63(12): 3839-3846.DOI: 10.3969/j.issn.0438-1157.2012.12.015. GU X, ZHU P N, LIU M S, et al. Modeling of gas-solid multi-way coupling of fluidization of slender particles in riser [J]. CIESC Journal, 2012, 63(12): 3839-3846.
[9]	李相鹏, 洪滔, 高增梁. 催化剂颗粒在弯道与渐扩管组合管系内的运动分布特征 [J]. 中南大学学报(自然科学版), 2012, 43(12): 4722-4728. LI X P, HONG T, Gao Z L. Motion and distribution of catalyst particles in pipe system combined with elbow and diverging tube [J]. Journal of Central South University (Science and Technology), 2012, 43(12): 4722-4728.
[10]	王福军. 计算流体动力学分析: CFD软件原理与应用[M]. 北京: 清华大学出版社, 2004: 221. WANG F J. Computational Fluid Dynamics Analysis: CFD Software Principles and Applications[M]. Beijing: Tsinghua University Press, 2004: 221.
[11]	王慧, 黄咏梅. 不同形状涡街发生体流场仿真及特性研究 [J]. 中国计量学院学报, 2013, 24(3): 237-242. WANG H, HUANG Y M. Fluid simulation and characteristic investigation for different vortex shedders [J]. Journal of China University of Metrology, 2013, 24(3): 237-242.
[12]	张颉, 张泽, 胡永锋. 高浓度电除尘器入口封头气固两相流动的近流线数值模拟 [J]. 化工学报, 2004, 55(9): 1448-1454. ZHANG J, ZHANG Z, HU Y F, et al. Close-to-streamline numerical simulation of gas-solid flow in high concentration ESP gas inlet hood [J]. Journal of Chemical Industry and Engineering(China), 2004, 55(9): 1449-1454.
[13]	TSAI R, HUANG J S. Combined effects of thermophoresis and electrophoresis on particle deposition onto a vertical flat plate from mixed convection flow through a porous medium [J]. Chemical Engineering Journal, 2010, 157(1): 52-59.
[14]	CHEN C L, CHAN K C. Combined effects of thermophoresis and electrophoresis on particle deposition onto a wavy surface disk [J]. International Journal of Heat & Mass Transfer, 2008, 51(11): 2657-2664.
[15]	BOLOGA A, SEIFERT H, PAUR H R, et al. Collection of fine particles by novel wet electrostatic precipitator [J]. IEEE Transactions on Industry Applications, 2010, 45(6): 2170-2177.
[16]	沈丹, 仲兆平, 过小玲. 600MW电厂SCR烟气脱硝反应器内不同导流板的流场数值模拟 [J]. 电力科技与环保, 2007, 23(1): 42-45. SHEN D, ZONG Z P, GUO X L. Numerical simulation of different guide plates in selective catalytic reduction denitrification reactor of 600MW power plant[J]. Electric Power Environmental Protection, 2007, 23(1): 42-45.
[17]	俞逾, 杨晨, 范莉. 电厂SCR系统的设计与数值模拟 [J]. 现代电力, 2007, 24(3): 58-62. YU Y, YANG C, FAN L. Design and numerical simulation for selective catalytic reduction system in power plant[J]. Modern Electric Power, 2007, 24(3): 59-61.
[18]	洪文鹏, 兰江. SCR脱硝系统静态混合器数值模拟 [J]. 锅炉技术, 2014, 45(3): 68-73. HONG W P, LAN J. Numerical simulation of static Mixer in static mixer in SCR denitrification system [J]. Boiler Technology, 2014, 45(3): 68-74.
[19]	杨超, 张杰群, 郭婷婷. SCR烟气脱硝装置烟气流场数值模拟 [J]. 东北电力大学学报, 2012, 32(1): 66-70. YANG C, ZHANG J Q, GUO T T. Numerical simulation of the flow field in a SCR system [J]. Journal of Northeast Dianli University, 2012, 32(1): 66-70.
[20]	JUN Y D, TABAKOFF W. Numerical simulation of a dilute particulate flow (laminar) over tube banks [J]. Journal of Fluids Engineering, 1994, 116(4): 770-777.
[21]	JOFRÉ V P, ASSOF M V, FANZONE M L, et al. Optimization of ultrasound assisted-emulsification-dispersive liquid-liquid microextraction by experimental design methodologies for the determination of sulfur compounds in wines by gas chromatography-mass spectrometry [J]. Analytica Chimica Acta, 2010, 683(1): 126-135.
[22]	NEUBURGER M, ROTZINGER M, KAISER H. A simplex method for function minimization [J]. Computer Journal, 1965, 7(4): 308-313.[J]. Journal of Fluids Engineering, 1994, 116(4):770-777.
[21]	Jofré V P, Assof M V, Fanzone M L, et al. Optimization of ultrasound assisted-emulsification-dispersive liquid-liquid microextraction by experimental design methodologies for the determination of sulfur compounds in wines by gas chromatography-mass spectrometry[J]. Analytica Chimica Acta, 2010, 683(1):126-135.
[22]	Neuburger M, Rotzinger M, Kaiser H. A Simplex Method for Function Minimization[J]. Computer Journal, 1965, 7(4):308-313.