含细长颗粒的洗涤冷却室内的多相分布特性
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摘要
采用改进的直接取样法,在按几何尺寸缩小的工业气化炉洗涤冷却室冷模装置内,同时测量不同操作条件下的轴径向局部固含率和气含率,对细长颗粒在洗涤冷却室内的多相分布特性进行研究。结果表明:以下降管出口截面为界,洗涤冷却室可分为上部气液固混合区和下部固液流动区,其中上部区域由下降管出口区、破泡板作用区和气垫层区组成,下部区域由气相湍动作用区、回流区和二次流动区组成;在颗粒阻碍效应减速沉降和团聚效应加速沉降的共同作用下,轴向固含率呈现波动分布;环隙气速、固相体积分数和长径比的增加均会增强床层的湍动,促进气体的径向扩散;操作条件的改变使颗粒的漂移速度发生改变,径向固含率分布出现波动;在气相扰动和回流作用下,二次流动区呈现环状流动,流体和颗粒的"壁面效应"使该区域的固含率呈现中心高边壁低的特点。
In order to study multi-phase distribution characteristics of slender particles in scrubbing-cooling chamber, an improved direct sampling method was used to simultaneously measure locally axial and radial distribution of solid concentration and gas holdup in a cold model apparatus at various operating conditions. The cold model apparatus was scaled down according to geometric dimensions of scrubbing-cooling chamber of industrial gasification system. The results showed that scrubbing-cooling chamber could be divided into two zones of the upper gas-liquid-solid mixing zone and the lower solid-liquid flowing zone with boundary at cross-section of the downcomer outlet. The gas-liquid-solid mixing zone was consisted of downcomer outlet, bubble-break plate and gas cap regions, while the solid-liquid flow zone was consisted of gas phase turbulence, recirculation, and secondary flow regions. Due to compounded effects of particle hindrance(slowed down sedimentation) and agglomeration(accelerated sedimentation), the axial distribution of solid concentration exhibited wavy fluctuations. The increase of annular gas velocity, solid volume concentration and aspect ratio of length over diameter enhanced bed turbulence and promoted radial gas dissipation. Change of operating conditions altered particle drifting velocity and resulted in fluctuation of radial solid concentration distribution. Under the effects of gas turbulence and recirculation, the secondary flow region showed circular flow where the "wall effect" of fluids and particles forced solid concentration higher at center but lower near wall.
In order to study multi-phase distribution characteristics of slender particles in scrubbing-cooling chamber, an improved direct sampling method was used to simultaneously measure locally axial and radial distribution of solid concentration and gas holdup in a cold model apparatus at various operating conditions. The cold model apparatus was scaled down according to geometric dimensions of scrubbing-cooling chamber of industrial gasification system. The results showed that scrubbing-cooling chamber could be divided into two zones of the upper gas-liquid-solid mixing zone and the lower solid-liquid flowing zone with boundary at cross-section of the downcomer outlet. The gas-liquid-solid mixing zone was consisted of downcomer outlet, bubble-break plate and gas cap regions, while the solid-liquid flow zone was consisted of gas phase turbulence, recirculation, and secondary flow regions. Due to compounded effects of particle hindrance(slowed down sedimentation) and agglomeration(accelerated sedimentation), the axial distribution of solid concentration exhibited wavy fluctuations. The increase of annular gas velocity, solid volume concentration and aspect ratio of length over diameter enhanced bed turbulence and promoted radial gas dissipation. Change of operating conditions altered particle drifting velocity and resulted in fluctuation of radial solid concentration distribution. Under the effects of gas turbulence and recirculation, the secondary flow region showed circular flow where the "wall effect" of fluids and particles forced solid concentration higher at center but lower near wall.
引文
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[28]OZOLINS A,STRAUTINS U.Simple models for wall effect in fiber suspension flows[J].Math.Model.Anal.,2014,19(1):75-84.
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[2]卢瑞华,王亦飞,苏宜丰,等.复合鼓泡床洗涤冷却室中液滴夹带统计模型[J].化学反应工程与工艺,2006,22(1):37-42.LU R H,WANG Y F,SU Y F,et al.Droplets statistics model for water entrainment in the separation zone of the compound bubbling chamber[J].Chemical Reaction Engineering and Technology,2006,22(1):37-42.
[3]王亦飞,陈意心,刘霞,等.新型洗涤冷却室内的气体带液问题[J].化学反应工程与工艺,2008,24(1):24-28.WANG Y F,CHEN Y X,LIU X,et al.Entraining liquid problem in a new type of scrubbing-cooling chamber[J].Chemical Reaction Engineering and Technology,2008,24(1):24-28.
[4]林岚,王亦飞,郭强强,等.液相性质对新型洗涤冷却室内液滴夹带的影响[J].过程工程学报,2011,11(5):742-746.LIN L,WANG Y F,GUO Q Q,et al.Effects of liquid properties on liquid entrainment in a new scrubbing-cooling chamber[J].The Chinese Journal of Process Engineering,2011,11(5):742-746.
[5]郭强强,王亦飞,潘飞,等.复合型洗涤冷却室内液滴夹带规律研究[J].中国电机工程学报,2014,34(11):1769-1778.GUO Q Q,WANG Y F,PAN F,et al.Research on droplet entrainment in the composite quench chamber[J].Proceedings of the CSEE,2014,34(11):1769-1778.
[6]王亦飞,吴宏涛,贺必云,等.新型旋流降膜式洗涤冷却环的开发与研究[J].华东理工大学学报(自然科学版),2005,31(6):752-755.WANG Y F,WU H T,HE B Y,et al.Development of a new rotary falling film quench ring for scrubbing and cooling hot syngas[J].Journal of East China University of Science and Technology(Natural Science Edition),2005,31(6):752-755.
[7]王灵萍,王亦飞,郭强强,等.洗涤冷却管内垂直降膜流动特性[J].化工学报,2013,64(6):1959-1968.WANG L P,WANG Y F,GUO Q Q,et al.Flow characteristics of vertical falling film in scrubbing-cooling pipe[J].CIESC Journal,2013,64(6):1959-1968.
[8]颜留成,王亦飞,王灵萍,等.洗涤冷却环内液体冷态流动行为数值模拟[J].化工学报,2014,65(8):2927-2933.YAN L C,WANG Y F,WANG L P,et al.Numerical simulation of cold state liquid flow in scrubbing-cooling ring[J].CIESC Journal,2014,65(8):2927-2933.
[9]YAN L C,WANG Y F,WU Z W,et al.Research of vertical falling film behavior in scrubbing-cooling tube[J].Chem.Eng.Res.Des.,2017,117:627-636.
[10]王晶,王亦飞,颜留成,等.管内垂直下降液膜速度与厚度分布特性[J].化工学报,2016,67(6):2239-2245.WANG J,WANG Y F,YAN L C,et al.Characteristics of velocity and thickness distribution of liquid film in vertical falling tube[J].CIESC Journal,2016,67(6):2239-2245.
[11]柴雪琴,王亦飞,尹柯,等.流体诱导下洗涤冷却室内部构件的振动特性[J].华东理工大学学报(自然科学版),2010,36(3):346-350.CHAI X Q,WANG Y F,YIN K,et al.Vibrational property of internal component in scrubbing-cooling chamber with flow induced[J].Journal of East China University of Science and Technology(Natural Science Edition),2010,36(3):346-350.
[12]陈程,徐峰,袁竹林,等.破泡结构对洗涤室内气泡特性的影响研究[J].热力发电,2011,40(7):24-27.CHEN C,XU F,YUAN Z L,et al.Study on influence of bubble-breaking structure upon the gas bubble properties in the scrubbing chamber[J].Thermal Power Generation,2011,40(7):24-27.
[13]付碧华.洗涤冷却室内部结构优化及热质传递过程的数值模拟[D].上海:华东理工大学,2012.FU B H.Structure optimization of WSCC and numerical simulation of heat and mass transfer process[D].Shanghai:East China University of Science and Technology,2012.
[14]贺必云.新型洗涤冷却室内多相流动特征的研究[D].上海:华东理工大学,2005.HE B Y.Study on multiphase flow characteristics of the new type of scrubbing-cooling chamber[D].Shanghai:East China University of Science and Technology,2005.
[15]吴晅.洗涤冷却室内气液固三相流动及热质传递规律研究[D].南京:东南大学,2009.WU X.Study on gas-liquid-solid flow and heat&mass transfer in scrubbing-cooling chamber[D].Nanjing:Southeast University,2009.
[16]吴晅,梁盼龙,王丽芳,等.气固两相流穿越液池过程颗粒运动及分布特性[J].化工学报,2015,66(3):905-914.WU X,LIANG P L,WANG L F,et al.Distribution properties and movement of particles in gas-solids flow passing through liquid bath[J].CIESC Journal,2015,66(3):905-914.
[17]付碧华,王亦飞,林岚,等.洗涤冷却管出口处的射流深度和界面波动特性[J].化工学报,2011,62(7):1817-1823.FU B H,WANG Y F,LIN L,et al.Penetration depth and characteristics of interface fluctuation at quenching pipe outlet[J].CIESC Journal,2011,62(7):1817-1823.
[18]龚晓波,顾兆林,林高平,等.水煤浆气化炉激冷流程中气液两相负浮力流动的数值模拟[J].化工学报,2003,54(7):930-935.GONG X B,GU Z L,LIN G P,et al.Numerical simulation of gas-liquid two-phase flow with reverse buoyancy in quench chamber of coal gasifier and its application[J].Journal of Chemical Industry and Engineering(China),2003,54(7):930-935.
[19]HUANG L Z,GAO X,LIN J Z.Cylindrical particulate internal flows:a review[J].Fron.Mech.Eng.,2012,7(4):385-393.
[20]GORE R A,CROWE C T.Effect of particle size on modulating turbulent intensity[J].Int.J.Multiphase Flow,1989,15(2):279-285.
[21]林建忠,林江,石兴.两相流中柱状固粒对流体湍动特性影响的研究[J].应用数学和力学,2002,23(5):483-488.LIN J Z,LIN J,SHI X.Research on the effect of cylinder particles on the turbulent properties in particulate flows[J].Applied Mathematics and Mechanics,2002,23(5):483-488.
[22]NASR-EL-DIN H A,MAC TAGGART R S,MASLIYAH J H.Local solids concentration measurement in a slurry mixing tank[J].Chem.Eng.Sci.,1996,51(8):1209-1220.
[23]GANDHI B,PRAKASH A,BERGOUGNOU M A.Hydrodynamic behavior of slurry bubble column at high solids concentrations[J].Powder Technol.,1999,103(2):80-94.
[24]曹俊雅,马斌,李向阳,等.测定气-液-固搅拌槽内相含率分布取样法的改进[J].黄金科学技术,2015,23(4):80-85.CAO J Y,MA B,LI X Y,et al.The improved sampling method for the measurement of phase holdup distributions in gas-liquid-solid stirred tank[J].Gold Science and Technology,2015,23(4):80-85.
[25]CARLSSON A,LUNDELL F,S?DERBERG D.The wall effect on the orientation of fibres in a shear flow[J].Ann.Trans.Nordic Rheol.Soc.,2006,14:83-89.
[26]HOLM R,S?DERBERG D.Shear influence on fibre orientation[J].Rheol.Acta,2007,46(5):721-729.
[27]KU X K,LIN J Z.Effect of two bounding walls on the rotational motion of a fiber in the simple shear flow[J].Fiber.Polym.,2009,10(3):302-309.
[28]OZOLINS A,STRAUTINS U.Simple models for wall effect in fiber suspension flows[J].Math.Model.Anal.,2014,19(1):75-84.
[29]OHNUKI A,AKIMOTO H.Experimental study on transition of flow pattern and phase distribution in upward air-water two-phase flow along a large vertical pipe[J].Int.J.Multiphase Flow,2000,26(3):367-386.
[30]DINH S M.On the rheology of concentrated fiber suspensions[D].Cambridge:Massachusetts Institute of Technology,1981.
[31]FOLGAR F,TUCKER C L.Orientation behavior of fibers in concentrated suspensions[J].J.Reinf.Plast.Comp.,1984,3(2):98-119.
[32]KUMAR P,RAMARAO B V.Enhancement of the sedimentation rates of fibrous suspensions[J].Chem.Eng.Commun.,1991,108(1):381-401.
[33]HERZHAFT B,GUAZZELLIé.Experimental study of the sedimentation of dilute and semi-dilute suspensions of fibres[J].J.Fluid Mech.,1999,384(4):133-158.
[34]唐家鹏.FLUENT14.0超级学习手册[M].北京:人民邮电出版社,2013:184-185.TANG J P.FLUENT14.0 Super Learning Manual[M].Beijing:Posts&Telecom Press,2013:184-185.
[35]张兆顺,崔桂香,许春晓.湍流理论与模拟[M].北京:清华大学出版社,2005:79.ZHANG Z S,CUI G X,XU C X.Theory and Modeling of Turbulence[M].Beijing:Tsinghua University Press,2005:79.
[36]MACKAPLOW M B,SHAQFEH E S G.A numerical study of the sedimentation of fibre suspensions[J].J.Fluid Mech.,1998,376:149-182.
[37]HERZHAFT B,GUAZZELLIé,MACKAPLOW M B,et al.Experimental investigation of the sedimentation of a dilute fiber suspension[J].Phys.Rev.Lett.,1996,77(2):290-293.