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CFD study on double-to single-loop flow pattern transition and its influence on macro mixing efficiency in fully baffled tank stirred by a Rushton turbine

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Chinese Journal of Chemical Engineering 2019年第5期27卷 993-1000页

作者： Quanhong Zhu Hang Xiao Aqiang Chen shujun geng Qingshan Huang Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao 266101China Dalian National Laboratory for Clean Energy Dalian 116023China Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

For a fully baffled tank stirred by a Rushton turbine (RT), the flow pattern will change from double- to single-loop as the off bottom clearance (C) of the RT decreases from one third of the tank diameter. Such a flow pattern transition as well as its influence on the macro mixing efficiency was investigated via CFD simulation. The transient sliding mesh approach coupled with the standard k-s turbulence model could correctly and efficiently reproduce the reported critical C range where the flow pattern changes. Simulation results indicated that such a critical C range varied hardly with the impeller rotation speed but decreased significantly with increasing impeller diameter. Small RTs are preferable to generating the single-loop flow pattern. A mechanism of the flow pattern transition was further proposed to explain these phe no mena. The discharge stream from the RT deviates down wards from the horizontal direction for small C values;if it meets the tank wall first, the double-loop will form;if it hits the tank bottom first, the single-loop will form. With the flow pattern transition, the mixing time decreased by about 35% at the same power input (P), indicating that the single-loop flow pattern was more efficient than the double-loop to enhance the macro mixing in the tank. A comparison was further made between the single-loop RT and pitched blade turbine (PBT, 45°) from macro mixing perspective. The single-loop RT was found to be less efficient than the PBT and usually required 60% more time to achieve the same level of macro mixing at the same P.

关键词： Rushton turbine Flow pattern Transition Simulation Mechanism Mixing

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Process Intensification in Pneumatically Agitated Slurry Reactors

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Engineering 2021年第3期7卷 304-325页

作者： shujun geng Zai-Sha Mao Qingshan Huang Chao Yang Key Llaboratory of Biofues Qingdao Institute of Eioenergy and Bioprocess TednologyChinese ALcadermy of SsciencesQingdao 266101China Dalian Narional Labor atary or dlean Energy Dalian lustitue of chemical PhysitsChinese Academy of SciancesDalian 11623China Key Laboratary of areen Proces and Engireering Iistitue of Poess Eingireeringhinese Academy of SdercesBeijing 100190Ohina

Pneumatically agitated slurry reactors,including bubble column reactors and airlift loop reactors(ALRs),are important gas-liquid-solid multiphase *** reactors have been widely applied in many processes,especially in the biological fermentation and energy chemical industry,due to their low shear stress,good mixing,perfect mass-/heat-transfer properties,and relatively low *** further improve the performance of slurry reactors(i.e.,mixing and mass/heat transfer)and to satisfy industrial require-ments(e.g.,temperature control,reduction of back-mixing,and product separation),the process intensi-fication of slurry reactors is *** article starts by reviewing the latest advancements in the intensification of mixing and mass/heat transfer in these two types of *** then summarizes process-intensification methods for mixing and separation that allow continuous production in these slurry ***-intensification technology that integrates directional flow in an ALR with simple solid-liquid separation in a hydrocyclone is recommended for its high efficiency and low *** arti-cle also systematically addresses vital considerations and challenges,including flow regime discrimina-tion,gas spargers,solid particle effects,and other concerns in slurry *** introduces the progress of numerical simulation using computational fluid dynamics(CFD)for the rational design of slurry reactors and discusses difficulties in ***,it presents conclusions and perspectives on the design of industrial slurry reactors.

关键词： Slurry reactors Pneumatic agitation Bubble column Airlift loop reactor Process intensification Solid particles

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Influences of top clearance and liquid throughput on the performances of an external loop airlift slurry reactor integrated mixing and separation

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1514-1521页

作者： Hongyan Liu Zhuo Li shujun geng Fei Gao Taobo He Qingshan Huang School of Chemical Engineering and Technology Hebei University of TechnologyTianjin 300130China Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)Chinese Academy of Sciences(CAS)Qingdao 266101China Dalian National Laboratory for Clean Energy(DNL) Dalian 116023China Petrochemical Research Institute China National Petroleum Corporation(CNPC)Beijing 100083China

A new developed external loop airlift slurry reactor, which was integrated with gas–liquid–solid three-phase mixing, mass transfer, and liquid–solid separation simultaneously, was deemed to be a promising slurry reactor due to its prominent advantages such as achieving continuous separation of clear liquid from slurry and cyclic utilization of solid particles without any extra energy, energy-saving, and intrinsic safety design. The principal operating parameters, including gas separator volume, handling capacity, and superficial gas velocity, are systematically investigated here to promote the capabilities of mixing, mass transfer, and yield in the pilot external loop airlift slurry reactor. The influences of top clearance and throughput of the clear liquid on flow regime and gas holdup in the riser, liquid circulating velocity, and volumetric mass transfer coefficient with a typical high solid holdup and free of particles are examined experimentally. It was found that increasing the gas separator volume could promote the liquid circulating velocity by about 14.0% at most. Increasing the handling capacity of the clear liquid from 0.9 m3·h-1 to 3.0 m3·h-1 not only could increase the output without any adverse consequences, but also could enhance the liquid circulating velocity as much as 97.3%. Typical operating conditions investigated here can provide some necessary data and guidelines for this new external loop airlift slurry reactor to upgrade its performances.

关键词： External loop airlift reactor Mixing Separation Hydrocyclone Hydrodynamics Mass transfer

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Impacts of solid physical properties on the performances of a slurry external airlift loop reactor integrating mixing and separation

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Chinese Journal of Chemical Engineering 2023年第3期55卷 1-12页

作者： Tian Zhang Qingshan Huang shujun geng Aqiang Chen Yan Liu Haidong Zhang School of Chemical Engineering Hebei University of TechnologyTianjin 300130China Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)Chinese Academy of Sciences(CAS)Qingdao 266101China Dalian National Laboratory for Clean Energy(DNL) Dalian 116023China Innovation Academy for Green Manufacture Institute of Process EngineeringCASBeijing 100190China Synthetic Biology Technology Innovation Center of Shandong Province Qingdao 266101China Shandong Energy Institute Qingdao 266101China

Solid physical properties are vital for the design, optimization, and scale-up of gas–liquid–solid multiphase reactors. The complex and interactional effects of the solid physical properties, including particle diameter, density, wettability, and sphericity, on the hydrodynamic behaviors in a new external airlift loop reactor(EALR) integrating mixing and separation are decoupled in this work. Two semi-empirical equations are proposed and validated to predict the overall gas holdup and liquid circulating velocity satisfactorily, and then the individual influence of such solid physical properties is further investigated. The results demonstrate that both the overall gas holdup in the riser and the liquid circulating velocity in the downcomer increase with the contact angle, but decrease with particle size, density, and ***, the impact of the particle size on the liquid circulating velocity is also profoundly revealed on a micro-level considering the particle size distribution. Moreover, the axial solid concentration distribution is discussed, and the uniformity of the slurry is described by the mixing index of the solid particles. The results show that a more homogeneous mixture can be achieved by adding finer particles other than attaining violent turbulence. Therefore, this work lays a foundation for the design, scale-up, and industrialization of the EALRs.

关键词： Slurry reactor Hydrodynamics Particle Mixing Solid physical property

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Two-fluid modeling of Geldart A particles in gas-solid micro-fluidized beds

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Particuology 2015年第4期13卷 118-127页

作者： Xiaoxing Liu Chuanqiang Zhu shujun geng Meiqin Yao Jinhui Zhan Guangwen Xu State Key Laboratory of Multi-phase Complex System Institute of Process Engineering Chinese Academy of Science Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

The fiuidization behavior of Geldart A particles in a gas-solid micro-fluidized bed was investigated by Eulerian-Eulerian numerical simulation. The commonly used Gidaspow drag model was tested first. The simulation showed that the predicted minimum bubbling velocities were significantly lower than the experimental data even when an extremely fine grid size （of approximately one particle diameter） was used. The modified Gibilaro drag model was therefore tested next. The predicted minimum bubbling velocity and bed voidage were in reasonable agreement with the experimental data available in literature. The experimentally observed regime transition phenomena from bubbling to slugging were also reproduced successfully in the simulations. Parametric studies indicated that the solid-wall boundary conditions had a significant impact on the predicted gas and solid flow behavior.

关键词： Micro-fluidized bed Geldart A particle Two-fluid model Boundary condition Drag model

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Discrete and continuum modeling of granular flow in silo discharge

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Particuology 2018年第1期16卷 127-138页

作者： Tian Tian Jinglin Su Jinhui Zhan shujun geng Guangwen Xu Xiaoxing Liu State Key Laboratory of Multi-Phase Complex System Institute of Process Engineering Chinese Academy of Science Beijing 100190 China University of Chinese Academy ofSdences Beijing 100049 China Sino-Danish Center for Education and Research Beijing 100190 China

Granular material discharge from a flat-bottomed silo has been simulated by using continuum modeling and a three-dimensional discrete-element method （DEM）. The predictive abilities of three commonly used frictional viscosity models （Schaeffer, S-S, and μ（I）） were evaluated by comparing them with the DEM data. The funnel-flow pattern （type C） and the semi-mass-flow pattern （type B） that was predicted by DEM simulations can be represented when the Schaeffer orμ（I） model is used, whereas the S-S model gives a consistent type-B flow pattern. All three models over-estimate the discharge rate compared with the DEM. The profiles of the solids volume fraction and the vertical velocity above the outlet show that the larger discharge rates given by the Schaeffer and μ（I） model result from an over-estimation of volume fraction, whereas the deviation in the S-S model stems from the failure to predict a solid vertical velocity and a volume fraction.

关键词： Silo Flow pattern Discharge rate Discrete-element model Frictional viscosity model

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Influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors

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Chinese Journal of Chemical Engineering 2022年第4期35卷 51-71页

作者： He Yang Aqiang Chen shujun geng Jingcai Cheng Fei Gao Qingshan Huang Chao Yang Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)Chinese Academy of Sciences(CAS)Qingdao 266101China Dalian National Laboratory for Clean Energy(DNL) Dalian 116023China Synthetic Biology Technology Innovation Center of Shandong Province Qingdao 266101China Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100080China Petrochemical Research Institute China National Petroleum Corporation(CNPC)Beijing 100083China

Slurry reactors are popular in many industrial processes,involved with numerous chemical and biological mixtures,solid particles with different concentrations and properties,and a wide range of operating *** factors can significantly affect the hydrodynamic in the slurry reactors,having remarkable effects on the design,scale-up,and operation of the slurry *** article reviews the influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry ***,the influence of fluid properties,including the density and viscosity of the individual liquid and gas phases and the interfacial tension,has been ***,the solid particle properties(i.e.,concentration,density,size,wettability,and shape)on the hydrodynamics have been discussed in detail,and some vital but often ignored features,especially the influences of particle wettability and shape,as well as the variation of surface tension because of solid concentration alteration,are highlighted in this ***,the variations of physical properties of fluids,hydrodynamics,and bubble behavior resulted from the temperature and pressure variations are also summarized,and the indirect influences of pressure on viscosity and surface tension are addressed ***,conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.

关键词： Multiphase reactors Fluid physical properties Particle Operating conditions Bubble column Airlift loop reactor

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位置检测器件(PSD)在承船厢水平偏差测量中的应用

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自动化仪表 2000年第7期21卷 19-21页

作者：耿世钧王宝光河北工业大学机械学院天津300130 天津大学天津300072

介绍采用位置敏感检测器件（ＰＳＤ）及微机技术测量承船厢的水平偏差程度。具体介绍以激光源作为ＰＳＤ的光位置输入信号，使ＰＳＤ输出与厢体四角位置有关的模拟量信号，然后经Ａ／Ｄ转换及微机技术运算，得出水平偏差的结果。

关键词：水平检测承船厢位置检测器件微机升船机

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132例缺血性糖尿病足溃疡患者局部病变的中医证候特征

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中医杂志 2022年第20期63卷 1958-1964页

作者：耿树军杨军莫爵飞中国中医科学院广安门医院北京市西城区100053

目的探讨缺血性糖尿病足溃疡患者局部病变中医证候特征。方法回顾性收集132例患者缺血性糖尿病足溃疡的32项症状体征指标数据,统计其出现的频数及百分比。采用因子分析法进行分析降维、归类处理。结果 32项指标中趺阳脉消失的出现频... 详细信息

目的探讨缺血性糖尿病足溃疡患者局部病变中医证候特征。方法回顾性收集132例患者缺血性糖尿病足溃疡的32项症状体征指标数据,统计其出现的频数及百分比。采用因子分析法进行分析降维、归类处理。结果 32项指标中趺阳脉消失的出现频率最高(100%),出现频率≥50%的症状体征依次为足部麻木(69.7%)、皮肤温度低(56.8%)、皮肤少华干燥脱屑(53.8%)。因子分析按照公共因子特征值大于1、且旋转后累计方差贡献率在80%以上的标准,确定为公共因子的个数是前6个,旋转后因子载荷平方和累积为93.466%。提炼出6个公共因子,第一公共因子主要反映湿热变量的信息,解释了原变量27.908%的信息;第二公共因子主要反映热毒变量的信息,解释了原变量27.333%的信息;第三公共因子主要反映湿邪困阻变量的信息,解释了原变量17.523%的信息;第四公共因子主要反映气血两亏变量的信息,解释了原变量10.856%的信息;第五公共因子主要反映寒邪凝滞变量的信息,解释了原变量5.656%的信息;第六公共因子主要反映血瘀变量的信息,解释了原变量4.191%的信息。结论缺血性糖尿病足溃疡的局部证候可以归结为湿热证、热毒证、湿阻证、气血两亏证、寒凝证、血瘀证6类基本证型。

关键词：缺血性糖尿病足溃疡局部辨证中医证候因子分析法

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喷射反应器内气液两相流体动力学特征

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化工进展 2018年第4期37卷 1257-1266页

作者：陈阿强黄青山耿淑君杨超中国科学院青岛生物能源与过程研究所山东青岛266101 中国科学院过程工程研究所中国科学院绿色过程与工程重点实验室北京100190

喷射反应器是一种重要的化工过程强化设备,可有效强化传质与传热过程、加快反应速率、提高反应产率,近年来在多个领域得到应用。本文对两种典型喷射反应器的结构及其工作原理进行了描述,系统地分析了各操作参数和结构参数对气体吸入量... 详细信息

喷射反应器是一种重要的化工过程强化设备,可有效强化传质与传热过程、加快反应速率、提高反应产率,近年来在多个领域得到应用。本文对两种典型喷射反应器的结构及其工作原理进行了描述,系统地分析了各操作参数和结构参数对气体吸入量和气泡直径的影响规律,指出研究气体吸入和气泡破碎两种机制的必要性。对采用计算流体力学方法模拟喷射反应器内气液两相流进行了分析,指出Mixture模型适合研究气体吸入量,无法准确描述气泡运动和破碎这两个重要过程,提出采用计算流体力学与群体平衡模型结合的方法进行模拟,关键在于建立适合喷射反应器的气泡破碎频率模型。另外,结合工业应用的实际情况,强调了加入催化剂颗粒相的多相流分析对于指导工业应用的重要意义。

关键词：喷射反应器气液两相流气体吸入量气泡计算流体力学

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