级间隙高度和表观气速对多级环流反应器混合和传质的影响
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摘要
针对应用广泛的简单多级环流反应器,研究了级间隙高度和表观气速对其混合和传质的影响规律。发现简单多级环流反应器的各级存在着非正常流动、过渡及正常流动三个典型流动状态,且流动状态的转变存在着受级间隙高度影响的两个临界表观气速,并提出了相应的预测模型。研究结果表明:级间隙高度越大,多级环流反应器内形成正常流型所需的表观气速越大;各级上升管和降液管的气含率会增高,且相同条件下第三级气含率最大,第二级次之,第一级气含率最小;各级的循环液速会增大,且第一级循环液速最大,第二级次之,第三级最小;混合时间会缩短,而传质系数会增大。本研究可为工业多级环流反应器的科学设计、放大和操作提供重要指导。
A simple multistage internal airlift loop reactor(MIALR), which has been widely employed in the chemical industry, was designed and investigated. The influences of interstage height and superficial gas velocity in the MIALR on the performance of the mixing and mass transfer were inspected. Three typical regimes, i.e., abnornal, transition and regular regimes, in the MIALR were observed and proposed in this work for the first time. There were two critical superficial gas velocities impacted by the interstage height in the MIALR for the flow regime transition, and two mathematical models were proposed here for the prediction of flow regimes. The results showed that a higher superficial gas velocity was desired for reaching a regular regime when the interstage height of the MIALR increased. In addition, the respective gas holdups in the riser and the downcomer would be promoted if there was an increment of the interstage height in the MIALR. The gas holdups in the riser and the downcomer at the third stage were the highest at the same conditions, and those at the first stage were the lowest among the three stages in the reactor. Moreover, the higher the interstage height, the higher the circulating liquid velocity in the downcomer was. The highest circulating velocity in the downcomer was measured at the first stage, and the lowest value was obtained at the third stage. Finally, a reduction of mixing time was gained when the interstage height increased, while an increase of volumetric mass transfer coefficient was obtained at the same conditions. Therefore, a guideline for the scientific design, scaling up and operating of this kind of industrial MIALRs was provided.
A simple multistage internal airlift loop reactor(MIALR), which has been widely employed in the chemical industry, was designed and investigated. The influences of interstage height and superficial gas velocity in the MIALR on the performance of the mixing and mass transfer were inspected. Three typical regimes, i.e., abnornal, transition and regular regimes, in the MIALR were observed and proposed in this work for the first time. There were two critical superficial gas velocities impacted by the interstage height in the MIALR for the flow regime transition, and two mathematical models were proposed here for the prediction of flow regimes. The results showed that a higher superficial gas velocity was desired for reaching a regular regime when the interstage height of the MIALR increased. In addition, the respective gas holdups in the riser and the downcomer would be promoted if there was an increment of the interstage height in the MIALR. The gas holdups in the riser and the downcomer at the third stage were the highest at the same conditions, and those at the first stage were the lowest among the three stages in the reactor. Moreover, the higher the interstage height, the higher the circulating liquid velocity in the downcomer was. The highest circulating velocity in the downcomer was measured at the first stage, and the lowest value was obtained at the third stage. Finally, a reduction of mixing time was gained when the interstage height increased, while an increase of volumetric mass transfer coefficient was obtained at the same conditions. Therefore, a guideline for the scientific design, scaling up and operating of this kind of industrial MIALRs was provided.
引文
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[20]CHANG J,MENG F D,WANG L Y,et al.CFD investigation of hydrodynamics,heat transfer and cracking reaction in a heavy oil riser with bottom airlift loop mixer[J].Chemical Engineering Science,2012,78:128-143.
[21]SIMCIK M,MOTA A,RUZICKA M C,et al.CFD simulation and experimental measurement of gas holdup and liquid interstitial velocity in internal loop airlift reactor[J].Chemical Engineering Science,2011,66(14):3268-3279.
[22]BEDNARZ A,WEBER B,JUPKE A.Development of a CFD model for the simulation of a novel multiphase counter-current loop reactor[J].Chemical Engineering Science,2017,161:350-359.
[23]HUANG Q,YANG C,YU G,et al.CFD simulation of hydrodynamics and mass transfer in an internal airlift loop reactor using a steady twofluid model[J].Chemical Engineering Science,2010,65(20):5527-5536.
[24]MUDDE R F,VAN DEN AKKER H E A.2D and 3D simulations of an internal airlift loop reactor on the basis of a two-fluid model[J].Chemical Engineering Science,2001,56(21/22):6351-6358.
[25]ZHANG W,YONG Y,ZHANG G,et al.Mixing characteristics and bubble behavior in an airlift internal loop reactor with low aspect ratio[J].Chinese Journal of Chemical Engineering,2014,22(6):611-621.
[26]ZHANG S,LV Z Y,MULLER D,et al.PBM-CFD investigation of the gas holdup and mass transfer in a lab-scale internal loop airlift reactor[J].IEEE Access,2017,5:2711-2719.
[27]WADAUGSORN K,LIMTRAKUL S,VATANATHAM T,et al.Hydrodynamic behaviors and mixing characteristics in an internal loop airlift reactor based on CFD simulation[J].Chemical Engineering Research&Design,2016,113:125-139.
[28]YANG C,MAO Z S.Numerical Simulation of Multiphase Reactors with Continuous Liquid Phase[M].London:Academic Press,2014.
[29]HEIJNEN J,HOLS J,VAN DER LANS R,et al.A simple hydrodynamic model for the liquid circulation velocity in a full-scale two-and three-phase internal airlift reactor operating in the gas recirculation regime[J].Chemical Engineering Science,1997,52(15):2527-2540.
[30]CHISTI M Y.Airlift Bioreactors[M].Elsevier Applied Science,1989.
[31]LIU M,ZHANG T,WANG T,et al.Experimental study and modeling on liquid dispersion in external-loop airlift slurry reactors[J].Chemical Engineering Journal,2008,139(3):523-531.
[32]COUVERT A,ROUSTAN M,CHATELLIER P.Two-phase hydrodynamic study of a rectangular air-lift loop reactor with an internal baffle[J].Chemical Engineering Science,1999,54(21):5245-
[33]李飞.新型多级环流反应器流体力学研究[D].北京:清华大学,2014.LI F.Study on the hydrodynamics of novel multistage airlift loop reactor[D].Beijing:Tsinghua University,2004.
[34]LI S,QI T,ZHANG Y,et al.Hydrodynamics of a multi-stage internal loop airlift reactor[J].Chemical Engineering&Technology,2009,32(1):80-85.
[35]YU W,WANG T F,SONG F F,et al.Investigation of the gas layer height in a multistage internal-loop airlift reactor[J].Industrial&Engineering Chemistry Research,2009,48(20):9278-9285.
[36]YU W,WANG T F,LIU M L,et al.Liquid backmixing and particle distribution in a novel multistage internal-loop airlift slurry reactor[J].Industrial&Engineering Chemistry Research,2008,47(11):3974-3982.
[37]IMAI Y,TAKEI H,MATSUMURA M.A simple Na2SO3 feeding method for KLa measurement in large-scale fermentors[J].Biotechnology and Bioengineering,1987,29(8):982-993.
[38]周宏宝.新型搅拌式生物冶金反应器的传递特性研究[D].北京:中国科学院过程工程研究所,2012.ZHOU H B.Study on transport characteristics of new type stirred reactors for biohydrometallurgy[D].Beijing:Institute of Process Engineering,Chinese Academy of Sciences,2012.
[39]KLEIN J,GODO S,DOLGOS O,et al.Effect of a gas-liquid separator on the hydrodynamics and circulation flow regimes in internal-loop airlift reactors[J].Journal of Chemical Technology and Biotechnology,2001,76(5):516-524.
[40]VAN BENTHUM W A J,VAN DER LANS R,VAN LOOSDRECHT M C M,et al.Bubble recirculation regimes in an internal-loop airlift reactor[J].Chemical Engineering Science,1999,54(18):3995-4006.
[41]GARCIA-CALVO E,RODRIGUEZ A,PRADOS A,et al.A fluid dynamic model for three-phase airlift reactors[J].Chemical Engineering Science,1999,54(13/14):2359-2370.
[2]GUO X,YAO L,HUANG Q.Aeration and mass transfer optimization in a rectangular airlift loop photobioreactor for the production of microalgae[J].Bioresource Technology,2015,190:189-195.
[3]HUANG Q,JIANG F,WANG L,et al.Design of photobioreactors for mass cultivation of photosynthetic organisms[J].Engineering,2017,3(3):318-329.
[4]黄青山,张伟鹏,杨超,等.环流反应器的流动、混合与传递特性[J].化工学报,2014,65(7):2465-2473.HUANG Q S,ZHANG W P,YANG C,et al.Characteristics of multiphase flow,mixing and transport phenomena in airlift loop reactor[J].CIESC Journal,2014,65(7):2465-2473.
[5]SIKULA I,JURASCIK M,MARKOS J.Modeling of fermentation in an internal loop airlift bioreactor[J].Chemical Engineering Science,2007,62(18/19/20):5216-5221.
[6]ABBAS G,ZHANG M,LI W,et al.Performance stability of a labscale internal-loop airlift bio-particle reactor under substrate concentration shocks for simultaneous partial nitrification and anaerobic ammonia oxidation[J].Separation and Purification Technology,2015,141:322-330.
[7]LUO H P,AL DAHHAN M H.Local characteristics of hydrodynamics in draft tube airlift bioreactor[J].Chemical Engineering Science,2008,63(11):3057-3068.
[8]刘孟媛,周丹丹,高琳琳,等.有机负荷条件对间歇式气提内循环反应器中好氧颗粒污泥形成的影响[J].环境科学,2012,33(10):3529-3534.LIU M Y,ZHOU D D,GAO L L,et al.Influence of organic loading rate on the start-up of a sequencing airlift aerobic granular reactor[J].Environmental Science,2012,33(10):3529-3534.
[9]ROCHA-RIOS J,QUIJANO G,THALASSO F,et al.Methane biodegradation in a two-phase partition internal loop airlift reactor with gas recirculation[J].Journal of Chemical Technology and Biotechnology,2011,86(3):353-360.
[10]HUANG Q,ZHANG W,YANG C.Modeling transport phenomena and reactions in a pilot slurry airlift loop reactor for direct coal liquefaction[J].Chemical Engineering Science,2015,135:441-451.
[11]CHEN Z B,HE Z W,TANG C C,et al.Performance and model of a novel multi-sparger multi-stage airlift loop membrane bioreactor to treat high-strength 7-ACA pharmaceutical wastewater:effect of hydraulic retention time,temperature and p H[J].Bioresource Technology,2014,167:241-250.
[12]SARAVANAN P,PAKSHIRAJAN K,SAHA P.Treatment of phenolics containing synthetic wastewater in an internal loop airlift bioreactor(ILALR)using indigenous mixed strain of Pseudomonas sp under continuous mode of operation[J].Bioresource Technology,2009,100(18):4111-4116.
[13]MOHANTY K,DAS D,BISWAS M N.Treatment of phenolic wastewater in a novel multi-stage external loop airlift reactor using activated carbon[J].Separation and Purification Technology,2008,58(3):311-319.
[14]HUANG Q,YANG C,YU G,et al.3-D simulations of an internal airlift loop reactor using a steady two-fluid model[J].Chemical Engineering&Technology,2007,30(7):870-879.
[15]HUANG Q,YANG C,YU G,et al.Sensitivity study on modeling an internal airlift loop reactor using a steady 2D two-fluid model[J].Chemical Engineering&Technology,2008,31(12):1790-1798.
[16]LI S,XUE T,QI T,et al.Flow and mass transfer characteristics of multi-sparger and multi-stage internal airlift loop reactor[J].Chemical Engineering,2013,41(7):38-41.
[17]YU W,WANG T,LIU M,et al.Bubble circulation regimes in a multistage internal-loop airlift reactor[J].Chemical Engineering Journal,2008,142(3):301-308.
[18]KILONZO P M,MARGARITIS A,BERGOUGNOU M A,et al.Influence of the baffle clearance design on hydrodynamics of a two riser rectangular airlift reactor with inverse internal loop and expanded gas-liquid separator[J].Chemical Engineering Journal,2006,121(1):17-26.
[19]LUO L,LIU F,XU Y,et al.Hydrodynamics and mass transfer characteristics in an internal loop airlift reactor with different spargers[J].Chemical Engineering Journal,2011,175:494-504.
[20]CHANG J,MENG F D,WANG L Y,et al.CFD investigation of hydrodynamics,heat transfer and cracking reaction in a heavy oil riser with bottom airlift loop mixer[J].Chemical Engineering Science,2012,78:128-143.
[21]SIMCIK M,MOTA A,RUZICKA M C,et al.CFD simulation and experimental measurement of gas holdup and liquid interstitial velocity in internal loop airlift reactor[J].Chemical Engineering Science,2011,66(14):3268-3279.
[22]BEDNARZ A,WEBER B,JUPKE A.Development of a CFD model for the simulation of a novel multiphase counter-current loop reactor[J].Chemical Engineering Science,2017,161:350-359.
[23]HUANG Q,YANG C,YU G,et al.CFD simulation of hydrodynamics and mass transfer in an internal airlift loop reactor using a steady twofluid model[J].Chemical Engineering Science,2010,65(20):5527-5536.
[24]MUDDE R F,VAN DEN AKKER H E A.2D and 3D simulations of an internal airlift loop reactor on the basis of a two-fluid model[J].Chemical Engineering Science,2001,56(21/22):6351-6358.
[25]ZHANG W,YONG Y,ZHANG G,et al.Mixing characteristics and bubble behavior in an airlift internal loop reactor with low aspect ratio[J].Chinese Journal of Chemical Engineering,2014,22(6):611-621.
[26]ZHANG S,LV Z Y,MULLER D,et al.PBM-CFD investigation of the gas holdup and mass transfer in a lab-scale internal loop airlift reactor[J].IEEE Access,2017,5:2711-2719.
[27]WADAUGSORN K,LIMTRAKUL S,VATANATHAM T,et al.Hydrodynamic behaviors and mixing characteristics in an internal loop airlift reactor based on CFD simulation[J].Chemical Engineering Research&Design,2016,113:125-139.
[28]YANG C,MAO Z S.Numerical Simulation of Multiphase Reactors with Continuous Liquid Phase[M].London:Academic Press,2014.
[29]HEIJNEN J,HOLS J,VAN DER LANS R,et al.A simple hydrodynamic model for the liquid circulation velocity in a full-scale two-and three-phase internal airlift reactor operating in the gas recirculation regime[J].Chemical Engineering Science,1997,52(15):2527-2540.
[30]CHISTI M Y.Airlift Bioreactors[M].Elsevier Applied Science,1989.
[31]LIU M,ZHANG T,WANG T,et al.Experimental study and modeling on liquid dispersion in external-loop airlift slurry reactors[J].Chemical Engineering Journal,2008,139(3):523-531.
[32]COUVERT A,ROUSTAN M,CHATELLIER P.Two-phase hydrodynamic study of a rectangular air-lift loop reactor with an internal baffle[J].Chemical Engineering Science,1999,54(21):5245-
[33]李飞.新型多级环流反应器流体力学研究[D].北京:清华大学,2014.LI F.Study on the hydrodynamics of novel multistage airlift loop reactor[D].Beijing:Tsinghua University,2004.
[34]LI S,QI T,ZHANG Y,et al.Hydrodynamics of a multi-stage internal loop airlift reactor[J].Chemical Engineering&Technology,2009,32(1):80-85.
[35]YU W,WANG T F,SONG F F,et al.Investigation of the gas layer height in a multistage internal-loop airlift reactor[J].Industrial&Engineering Chemistry Research,2009,48(20):9278-9285.
[36]YU W,WANG T F,LIU M L,et al.Liquid backmixing and particle distribution in a novel multistage internal-loop airlift slurry reactor[J].Industrial&Engineering Chemistry Research,2008,47(11):3974-3982.
[37]IMAI Y,TAKEI H,MATSUMURA M.A simple Na2SO3 feeding method for KLa measurement in large-scale fermentors[J].Biotechnology and Bioengineering,1987,29(8):982-993.
[38]周宏宝.新型搅拌式生物冶金反应器的传递特性研究[D].北京:中国科学院过程工程研究所,2012.ZHOU H B.Study on transport characteristics of new type stirred reactors for biohydrometallurgy[D].Beijing:Institute of Process Engineering,Chinese Academy of Sciences,2012.
[39]KLEIN J,GODO S,DOLGOS O,et al.Effect of a gas-liquid separator on the hydrodynamics and circulation flow regimes in internal-loop airlift reactors[J].Journal of Chemical Technology and Biotechnology,2001,76(5):516-524.
[40]VAN BENTHUM W A J,VAN DER LANS R,VAN LOOSDRECHT M C M,et al.Bubble recirculation regimes in an internal-loop airlift reactor[J].Chemical Engineering Science,1999,54(18):3995-4006.
[41]GARCIA-CALVO E,RODRIGUEZ A,PRADOS A,et al.A fluid dynamic model for three-phase airlift reactors[J].Chemical Engineering Science,1999,54(13/14):2359-2370.