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Prediction of gas holdup in Bubble Columns Using Artificial Neural Network

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Chinese Journal of Chemical Engineering 2003年第2期11卷 162-165页

作者：吴元欣罗湘华陈启明李定或李世荣 M.H.Al-Dahhan M.P.Dudukovic Department of Chemical Engineering Wuhan Institute of Chemical Technology Department of Chemical Engineering Washington University St.Louis

A new correlation for the prediction of gas hold up in bubble columns was proposed based on an extensive experimental database set up from the literature published over last 30 years. The updated estimation method relying on artificial neural network, dimensional analysis and phenomenological approaches was used and the model prediction agreed with the experimental data with average relative error less than 10%.

关键词： bubble column gas holdup artificial neural network correlations

Experimental determination of gas holdup and volumetric mass transfer coefficient in a jet bubbling reactor

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Chinese Journal of Chemical Engineering 2021年第6期34卷 61-67页

作者： Mostafa Abbasian-arani Mohammad Sadegh Hatamipour Amir Rahimi Chemical Engineering Department University of IsfahanIsfahanIran

The hydrodynamics and mass transfer characteristics of a lab-scale jet bubbling reactor(JBR)including the gas holdup,volumetric mass transfer coefficient and specific interfacial area were assessed experimentally investigating the influence of temperature,pH and superficial gas *** reactor diameter and height were 11 and 30 cm,*** was equipped with a single sparger,operating at atmospheric pressure,20 and 40℃,and two pH values of 3 and *** height of the liquid was 23 cm,while the superficial gas velocity changed within 0.010-0.040 m·s^(-1)*** were conducted with pure oxygen as the gas phase and saturated lime solution as the liquid *** liquid-side volumetric mass transfer coefficient was determined under unsteady-state oxygen absorption in a saturated lime *** gas holdup was calculated based on the liquid height change,while the specific interfacial area was obtained by a physical method based on the bubble size distribution(BSD)in different superficial gas *** results indicated that at the same temperature but different pH,the gas holdup variation was negligible,while the liquid-side volumetric mass transfer coefficient at the pH value of 6 was higher than that at the pH=*** a constant pH but different temperatures,the gas holdup and the liquid-side volumetric mass transfer coefficients at 40℃were higher than that of the same at 20℃.A reasonable and appropriate estimation of the liquid-side volumetric mass transfer coefficient(kla)in a pilot-scale JBR was provided which can be applied to the design and scale-up of JBRs.

关键词： Jet bubbling reactor Liquid-side volumetric mass transfer coefficient gas holdup Specific interfacial area Experimental analysis

Simple Model for gas holdup and Liquid Velocity of Annular Photocatalytic External-Loop Airlift Reactor Under both Bubble and Developing Slug Flow

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Transactions of Tianjin University 2016年第3期22卷 228-236页

作者：王一平陈为强黄群武冯加和崔勇 School of Chemical Engineering and Technology Tianjin University Research Institute of Architectural Design & Urban Planning Tianjin University

Based on the momentum conservation approach, a theoretical model was developed to predict the superficial liquid velocity, and a correlation equation was established to calculate the gas holdup of an annular external-loop airlift reactor(AELAR)in the bubble flow and developing slug flow pattern. Experiments were performed by using tap-water and silicone oil with the viscosity of 2.0 mm^2/s(2cs-SiO)and 5.0 mm^2/s(5cs-SiO)as liquid phases. The effects of liquid viscosity and flow pattern on the AELAR performance were investigated. The predictions of the proposed model were in good agreement with the experimental results of the AELAR. In addition, the comparison of the experimental results shows that the proposed model has good accuracy and could be used to predict the gas holdup and liquid velocity of an AELAR operating in bubble and developing flow pattern.

关键词： gas holdup liquid velocity annular external airlift bubble flow slug flow

Effects of particle size and concentration on bubble coalescence and froth formation in a slurry bubble column

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Particuology 2018年第1期16卷 82-95页

作者： A.R. Sarhan J. Naser G. Brooks Department of Mechanical and Product Design Engineering Swinburne University of Technology Hawthorn Victoria 3122 Australia Department of Mechanical Engineering University ofAnbar Ramadi Anbar 31001 lraq

A new approach for simulating the formation of a froth layer in a slurry bubble column is proposed. Froth is considered a separate phase, comprised of a mixture of gas, liquid, and solid. The simulation was carried out using commercial flow simulation software （FIRE v2014） for particle sizes of 60-150 μm at solid concentrations of 0-40vol%, and superficial gas velocities of 0.02-0.034m/s in a slurry bubble column with a hydraulic diameter of 0.2 m and height of 1.2 m. Modelling calculations were conducted using a Eulerian-Eulerian multiphase approach with k-ε turbulence. The population balance equations for bubble breakup, bubble coalescence rate, and the interfacial exchange of mass and momentum were included in the computational fluid dynamics code by writing subroutines in Fortran to track the number density of different bubble sizes. Flow structure, radial gas holdup, and Sauter mean bubble diameter distributions at different column heights were predicted in the pulp zone, while froth volume fraction and density were predicted in the froth zone. The model was validated using available experimental data, and the predicted and experimental results showed reasonable agreement. To demonstrate the effect of increasing solid concentration on the coalescence rate, a solid-effect multiplier in the coalescence effi- ciency equation was used. The solid-effect multiplier decreased with increasing slurry concentration, causing an increase in bubble coalescence efficiency. A slight decrease in the coalescence efficiency was also observed owing to increasing particle size, which led to a decrease in Sauter mean bubble diam- eter. The froth volume fraction increased with solid concentration. These results provide an improved understanding of the dynamics of slurry bubble reactors in the presence of hydrophilic particles.

关键词： Computational fluid dynamics Slurry concentration gas holdup Particle size Froth Coalescence efficiency

gas dispersion and solid suspension in a three-phase stirred tank with triple impellers

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Chinese Journal of Chemical Engineering 2020年第5期28卷 1195-1202页

作者： Hanbin Wang Zhengming Gao Bingjie Wang Yuyun Bao Ziqi Cai State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China

The hydrodynamics is still not fully understood in the three-phase stirred tank equipped with multi-impeller due to the intensive interaction between *** this work,the solid critical suspension speed(NJSG),relative power demand(RPD)and overall gas holdup(ε_G)were measured in an air–water–glass beads stirred tank equipped with multi-impeller,which consists of a parabolic blade disk turbine below two down-pumping *** show that either the NJSGor the specific power consumption increases when increasing the volumetric solid concentration or superficial gas *** changes less than 10%when solid volumetric concentration ranges from 0 to 15%.ε_G decreases with the increase of solid concentration,and increases with the increase of both superficial gas velocity and the total specific power *** quantitative correlations of NJSG,RPD andεGwere regressed as the function of superficial gas velocity,specific power consumption,Froude number and gas flow number,in order to provide the reference in the design of such three-phase stirred tank with similar multi-impellers.

关键词： Solid suspension gas holdup gas-liquid-solid system Stirred reactor

Study on gas–liquid flow characteristics in stirred tank with dual-impeller based on CFD-PBM coupled model

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Chinese Journal of Chemical Engineering 2021年第10期34卷 63-75页

作者： Songsong Wang Qiuxiang Bu Deyu Luan Ying Zhang Longbin Li Zhaorui Wang Wenhao Shi College of Electromechanical Engineering Qingdao University of Science and TechnologyQingdao 266061China

Study on gas–liquid flow in stirred tank with two combinations of dual-impeller(six-bent-bladed turbine(6BT)+six-inclined-blade down-pumping turbine(6 ITD),the six-bent-bladed turbine(6BT)+six-inclinedblade up-pumping turbine(6ITU))was conducted using computational fluid dynamics(CFD)and population balance model(PBM)(CFD-PBM)coupled *** local bubble size was captured by particle image velocimetry(PIV)*** gas holdup,bubble size distribution and gas–liquid interfacial area were explored at different conditions through numerical *** results showed that the 4 mm bubbles accounted for the largest proportion of 33%at the gas flow rates Q=0.76 m^(3)·h^(-1) and 22%at Q=1.52 m^(3)·h^(-1) for combined impeller of 6BT+6ITU,while the bubbles of 4.7 mm and 5.5 mm were the largest proportion for 6BT+6ITD combination,i.e.25%at Q=0.76 m^(3)·h^(-1) and 22%at Q=1.52 m^(3)·h^(-1),respectively,which indicated that 6BT+6ITU could reduce bubble size effectively and promote gas *** addition,the gas holdup around impellers was increased obviously with the speed compared with gas flow *** it was concluded that 6ITU impeller could be more conductive to the bubble dispersion with more uniform bubble size,which embodied the advantages of 6BT+6ITU combination in gas–liquid mixing.

关键词： gas-liquid two-phase flow gas holdup gas-liquid interfacial area Bubble Coupling algorithm of CFD-PBM

Hydrodynamic behavior of an airlift reactor with net draft tube with different configurations: Numerical evaluation using CFD technique

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Particuology 2020年第4期18卷 91-108页

作者： Reza Salehpour Elham Jalilnejad Mehran Nalband Kamran Ghasemzadeh Faculty of Chemical Engineering Urmia University of TechnologyUrmiaIran

In terms of gas holdup,liquid velocity,and volumetric mass transfer coefficient for oxygen(KLa),the hydrodynamic behavior of four configurations of an airlift reactor(ALR)with a net draft tube(NDT)of different net mesh sizes(ALR-NDT-3,6,12,and ALR)have been numerically simulated for a range of inlet air flow *** effect of various levels of ratio of height(H)to inner tube diameter(D)of the net draft tube(H/D:9.3,10.7,17.5,and 20)and ratio of inner cross-sectional area of the riser(Ar)to the inner cross sectional area of the downcomer(Ad)(Ad/Ar:1.3 and 7)for different air flow rates is also evaluated for each reactor configuration operating with an air-water *** two-fluid formulation coupled with the k-εturbulence model is used for computational fluid dynamics(CFD)analysis of flow with Eulerian descriptions for the gas and liquid *** between air bubbles and liquid are taken into account using momentum exchange and drag coefficient based on two different *** in the predicted dynamical behavior are similar to those found experimentally.A good agreement was achieved suggesting that geometric effects are properly accounted for by the CFD *** a comparison with experimental data,numerical simulations show significant enhanced gas holdup,liquid velocity,and Kta for the ALR-NDTs compared with the conventional *** gas holdup values are achieved for ALR-NDT-3 than that for the other ALRs because it acts like a bubble column reactor as the holes present in the NDT are *** liquid velocities are seen in ALR-NDT-12,which operates like a conventional ***,the interaction between the NDT and upward gas flow leads to cross flow through the net,small bubbles,and high interfacial area as well as good mass *** was significant in ALR-NDT-6 with maximum Kta value of 0.031 *** applied methodology provides an insightful understanding of the complex dynamic behavior of ALR-NDTs and may be helpful in op

关键词： Airlift reactor Net draft tube Hydrodynamic behavior Computational fluid dynamics(CFD) gas holdup Mass transfer coefficient

Influence of impeller diameter on overall gas dispersion properties in a sparged multi-impeller stirred tank

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Chinese Journal of Chemical Engineering 2015年第6期23卷 890-896页

作者：包雨云王冰洁林明丽高正明杨杰 State Key Laboratory of Chemical Resource Engineering School of Chemical Engineering Beijing University of Chemical Technology

The impeller configuration with a six parabolic blade disk turbine below two down-pumping hydrofoil propellers, identified as PDT + 2CBY, was used in this study. The effect of the impeller diameter D, ranging from0.30 T to 0.40T(T as the tank diameter), on gas dispersion in a stirred tank of 0.48 m diameter was investigated by experimental and CFD simulation methods. Power consumption and total gas holdup were measured for the same impeller configuration PDT + 2CBY with four different D/T. Results show that with D/T increases from 0.30 to 0.40, the relative power demand(RPD) in a gas–liquid system decreases slightly. At low superficial gas velocity VSof 0.0078 m·s-1, the gas holdup increases evidently with the increase of D/T. However, at high superficial gas velocity, the system with D/T = 0.33 gets a good balance between the gas recirculation and liquid shearing rate, which resulted in the highest gas holdup among four different D/T. CFD simulation based on the two-fluid model along with the Population Balance Model(PBM) was used to investigate the effect of impeller diameter on the gas dispersion. The power consumption and total gas holdup predicted by CFD simulation were in reasonable agreement with the experimental data.

关键词： gas holdup Mixing Multiphase reactors Relative power demand CFD Multi-impeller stirred tank

Effect of gas Injection on Fluid Flow in Mold

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International Journal of Minerals,Metallurgy and Materials 1998年第1期12卷 16-19页

作者： Jiongming Zhang Wanjun Wang Jicheng He Baokuan Li (Materials Science and Engineering School, University of Science and Technology Beijing, Beijing 1 00083, China)(Northeastern University, Xi’an, China) Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China Northeastern University Xi'an China

A mathematical and physical model was adopted to compute the fluid flow distribution in case of localgas holdup in mold. The photography was used to show the fluid field. The predicted flow patterns show. reasonableag... 详细信息

关键词： mold gas holdup fluid field