喷射环流反应器的放大效应
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摘要
实验测量了两种塔径(?200和?500mm)和两种操作模式(气体单独喷射和气液同轴喷射)下喷射环流反应器内的全塔平均气含率、局部气含率及轴向液速径向分布、循环液速,归纳出全塔平均气含率的关联式。实验发现,喷射环流反应器具有十分显著的放大效应。小塔(?200)与大塔(?500)中的全塔平均气含率存在很大差异:小塔的全塔平均气含率～气速关系曲线比大塔陡峭,低气速下小塔气含率低于大塔、较高气速下高于大塔。根据漂移通量法分析得到小塔中流型转变点在表观气速0.1 m·s~(-1)左右,在实验气速范围内只存在拟均匀鼓泡流;大塔中流型转变点在表观气速0.04 m·s~(-1)左右,随气速增大从拟均匀鼓泡流转变为湍动鼓泡流。喷射环流反应器比气升式环流反应器、一般鼓泡塔全塔平均气含率略低,但循环液速更大,适用于强化固体悬浮与混合的气液固三相反应过程。
Effects of column diameter(? 200 and ? 500 mm) and operating mode(gas jet and gas-liquid co-injection) on flow dynamics including overall gas holdup, radial distributions of local gas holdup, axial liquid velocity and liquid circulation velocity were experimentally studied in a gas-liquid jet-loop reactor(JLR). A modified drift-flux model was developed to predict the overall gas holdup at various superficial gas velocities. The results show that the scale-up effect in the JLR is significant. The overall gas holdups in the small column(? 200 mm) and large column(? 500 mm) are different. The curve of "overall gas holdup-gas velocity" in the small column is steeper than that in the large column, which indicates that the overall gas holdup in the small column at low superficial gas velocities is smaller than that in the large column, while the opposite is true at high gas velocities. According to the drift-flux method, the flow regime transition point in the small column is at superficial gas velocity of 0.1 m·s~(-1), which means that a pseudo-homogeneous flow regime prevails under the present superficial gas velocity range. However, this value is 0.04 m·s~(-1) in the large column, and the flow regime is transferred from the pseudo-homogeneous flow to turbulent flow with the increase of gas velocity. Comparing to airlift reactors and bubble columns, JLRs have slightly lower overall gas holdup, while its liquid circulation velocity is distinctly higher, which indicates that JLR is more suitable for gas-liquid-solid three phase reactions for intensification of solid suspension and mixture.
Effects of column diameter(? 200 and ? 500 mm) and operating mode(gas jet and gas-liquid co-injection) on flow dynamics including overall gas holdup, radial distributions of local gas holdup, axial liquid velocity and liquid circulation velocity were experimentally studied in a gas-liquid jet-loop reactor(JLR). A modified drift-flux model was developed to predict the overall gas holdup at various superficial gas velocities. The results show that the scale-up effect in the JLR is significant. The overall gas holdups in the small column(? 200 mm) and large column(? 500 mm) are different. The curve of "overall gas holdup-gas velocity" in the small column is steeper than that in the large column, which indicates that the overall gas holdup in the small column at low superficial gas velocities is smaller than that in the large column, while the opposite is true at high gas velocities. According to the drift-flux method, the flow regime transition point in the small column is at superficial gas velocity of 0.1 m·s~(-1), which means that a pseudo-homogeneous flow regime prevails under the present superficial gas velocity range. However, this value is 0.04 m·s~(-1) in the large column, and the flow regime is transferred from the pseudo-homogeneous flow to turbulent flow with the increase of gas velocity. Comparing to airlift reactors and bubble columns, JLRs have slightly lower overall gas holdup, while its liquid circulation velocity is distinctly higher, which indicates that JLR is more suitable for gas-liquid-solid three phase reactions for intensification of solid suspension and mixture.
引文
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[23]CHISTI M Y,MOO-YOUNG M.Airlift reactors:characteristics,applications and design considerations[J].Chemical Engineering Communications,1987,60(1/2/3/4/5/6):195-242.
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[29]AKITA K,YOSHIDA F.Bubble size,interfacial area,and liquid-phase mass-transfer coefficient in bubble columns[J].Industrial&Engineering Chemistry Process Design and Development,1974,13(1):84-91.
[30]张煜,王丽军,李希.湍动浆态床流体力学研究(Ⅱ)轴向浆料速度的径向分布[J].化工学报,2008,59(12):3003-3009.ZHANG Y,WANG L J,LI X.Studies on hydrodynamics of slurry turbulent bubble column(Ⅱ)axial liquid and slurry velocity distribution.[J].Journal of Chemical Industry and Engineering,2008,59(12):3003-3009.
[31]WONGSUCHOTO P,PAVASANT P.Internal liquid circulation in annulus sparged internal loop airlift contactors[J].Chemical Engineering Journal,2004,100(1/2/3):1-9.
[32]AZHER N.E,GOURICH B,VIAL C,et al.Influence of alcohol addition on gas hold-up,liquid circulation velocity and mass transfer coefficient in a split-rectangular airlift bioreactor[J].Biochemical Engineering Journal,2005,23(2):161-167.
[33]LUO H,AL-DAHHAN M.Local characteristics of hydrodynamics in draft tube airlift bioreactor[J].Chemical Engineering Science,2008,63(11):3057-3068.
[34]ZIEGENHEIN T,ZALUCKY J,RZEHAK R,et al.On the hydrodynamics of airlift reactors,Part I:Experiments[J].Chemical Engineering Science,2016,150:54-65.
[2]WARMELING H,BEHR A,VORHOLT A J.Jet loop reactors as a versatile reactor set up-intensifying catalytic reactions:a review[J].Chemical Engineering Science,2016,149:229-248.
[3]SHAIKH A,AL-DAHHAN M.Scale-up of bubble column reactors:a review of current state-of-the-art[J].Industrial&Engineering Chemistry Research,2013,52(24):8091-8108.
[4]FAN L S,HWANG S J,MATSUURA A.Hydrodynamic behavior of a draft tube gas-liquid solid spouted bed[J].Chemical Engineering Science,1984,39(12):1677-1688.
[5]张宝泉,胡宗定.喷射式环流反应器的研究[J].化工学报,1989,40(6):733-740.ZHANG B Q,HU Z D.Experimental study of jet-loop reactor[J].Journal of Chemical Industry and Engineering,1989,40(6):733-740.
[6]王一平,胡宗定.喷射环流三相流化床反应器轴向液速分布的研究[J].化学反应工程与工艺,1990,6(1):57-62.WANG Y P,HU Z D.Study on the liquid velocity distribution along the axis of a jet loop three-phase fluidized bed reactor[J].Chemical Reaction Engineering and Technology,1990,6(1):57-62.
[7]FADAVI A,CHISTI Y.Gas holdup and mixing characteristics of a novel forced circulation loop reactor[J].Chemical Engineering Journal,2007,131(1/2/3):105-111.
[8]卢浩然,高用祥,成有为,等.喷射型环流反应器中气含率和液速的分布[J].高校化学工程学报,2017,31(5):1088-1095.LU H R,GAO Y X,CHENG Y W,et al.Gas holdup and liquid velocity distribution in a jet loop reactor[J].Journal of Chemical Engineering of Chinese Universities,2017,31(5):1088-1095.
[9]GAO Y,HONG D,LU H,et al.Gas holdup and liquid velocity distributions in the up flow jet-loop reactor[J].Chemical Engineering Research and Design,2018,136:94-104.
[10]PIRONTI F F,MEDINA V R,CALVO R,et al.Effect of draft tube position on the hydrodynamics of a draft tube slurry bubble column[J].Chemical Engineering Journal,1995,60(1/2/3):155-160.
[11]WILKINSON P M,SPEK A P,VAN DIERENDONCK L L.Design parameters estimation for scale-up of high-pressure bubble columns[J].AIChE Journal,1992,38(4):544-554.
[12]RUZICKA M,DRAHOS J,FIALOVA M,et al.Effect of bubble column dimensions on flow regime transition[J].Chemical Engineering Science,2001,56(21):6117-6124.
[13]BESAGNI G,GALLAZZINI L,INZOLI F.On the scale-up criteria for bubble columns[J].Petroleum,2017.
[14]VAN BATEN J M,ELLENBERGER J,KRISHNA R.Hydrodynamics of internal air-lift reactors:experiments versus CFDsimulations[J].Chemical Engineering and Processing,2003,42(10):733-742.
[15]HEIJNEN J J,HOLS J,VANDERLANS R,et al.A simple hydrodynamic model for the liquid circulation velocity in a full-scale twoand three-phase internal airlift reactor operating in the gas recirculation regime[J].Chemical Engineering Science,1997,52(15):2527-2540.
[16]KRISHNA R,DESWART J,ELLENBERGER J,et al.Gas holdup in slurry bubble columns:effect of column diameter and slurry concentrations[J].AIChE Journal,1997,43(2):311-316.
[17]KRISHNA R,SIE S T.Design and scale-up of the Fischer-Tropsch bubble column slurry reactor[J].Fuel Processing Technology,2000,64(1/2/3):73-105.
[18]FORRET A,SCHWEITZER J M,GAUTHIER T,et al.Influence of scale on the hydrodynamics of bubble column reactors:an experimental study in columns of 0.1,0.4 and 1 m diameters[J].Chemical Engineering Science,2003,58(3/4/5/6):719-724.
[19]KOIDE K,HORIBE K,KAWABATA H,et al.Gas holdup and volumetric liquid-phase mass transfer coefficient in solid-suspended bubble column with draught tube[J].Journal of Chemical Engineering of Japan,1985,18(3):248-254.
[20]VESVIKAR M S,AL-DAHHAN M.Effect of scale on hydrodynamics of internal gas-lift loop reactor-type anaerobic digester using CFD[J].Chemical Product and Process Modeling,2015,10(3):179-192.
[21]WALLIS G B.One-dimensional two-phase flow[M].New York:McGraw-Hill,1969.
[22]BESAGNI G,INZOLI F.Comprehensive experimental investigation of counter-current bubble column hydrodynamics:holdup,flow regime transition,bubble size distributions and local flow properties[J].Chemical Engineering Science,2016,146:259-290.
[23]CHISTI M Y,MOO-YOUNG M.Airlift reactors:characteristics,applications and design considerations[J].Chemical Engineering Communications,1987,60(1/2/3/4/5/6):195-242.
[24]DECKWER W,FIELD R W.Bubble column reactors[M].New York:Wiley,1992.
[25]张煜.湍动鼓泡塔充分发展段的流体力学与内构件技术研究[D].杭州:浙江大学,2011.ZHANG Y.Hydrodynamics of turbulent bubble column with internals in well-developed flow region[D].Hangzhou:Zhejiang University,2011.
[26]ZUBER N,FINDLAY J.Average volumetric concentration in two-phase flow systems[J].Journal of Heat Transfer,1965,87(4):453-468.
[27]SAXENA S C,CHEN Z D.Hydrodynamics and heat-transfer of baffled and unbaffled slurry bubble-columns[J].Reviews in Chemical Engineering,1994,10(3/4):195-400.
[28]SCHILLER V L.A drag coefficient correlation[J].Zeitschrift Des Vereins Deutscher Ingenieure,1933,77:318-320.
[29]AKITA K,YOSHIDA F.Bubble size,interfacial area,and liquid-phase mass-transfer coefficient in bubble columns[J].Industrial&Engineering Chemistry Process Design and Development,1974,13(1):84-91.
[30]张煜,王丽军,李希.湍动浆态床流体力学研究(Ⅱ)轴向浆料速度的径向分布[J].化工学报,2008,59(12):3003-3009.ZHANG Y,WANG L J,LI X.Studies on hydrodynamics of slurry turbulent bubble column(Ⅱ)axial liquid and slurry velocity distribution.[J].Journal of Chemical Industry and Engineering,2008,59(12):3003-3009.
[31]WONGSUCHOTO P,PAVASANT P.Internal liquid circulation in annulus sparged internal loop airlift contactors[J].Chemical Engineering Journal,2004,100(1/2/3):1-9.
[32]AZHER N.E,GOURICH B,VIAL C,et al.Influence of alcohol addition on gas hold-up,liquid circulation velocity and mass transfer coefficient in a split-rectangular airlift bioreactor[J].Biochemical Engineering Journal,2005,23(2):161-167.
[33]LUO H,AL-DAHHAN M.Local characteristics of hydrodynamics in draft tube airlift bioreactor[J].Chemical Engineering Science,2008,63(11):3057-3068.
[34]ZIEGENHEIN T,ZALUCKY J,RZEHAK R,et al.On the hydrodynamics of airlift reactors,Part I:Experiments[J].Chemical Engineering Science,2016,150:54-65.