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Variation law of gas holdup in an autoclave during the pressure leaching process by using a mixed-flow agitator

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International Journal of Minerals,Metallurgy and Materials 2017年第8期24卷 876-883页

作者： Lei Tian Yan Liu Jun-jie Tang Guo-zhi Lü Ting-an Zhang Key Laboratory of Ecological Utilization of Multi-Metal Intergrown Ores of the Ministry of Education School of Materials and Metallurgy Northeastern University School of Metallurgical and Chemical Engineering Jiangxi University of Science and Technology

The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham's theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10^(-11)n^(3.65)T^(2.08)P_g^(0.18). It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.

关键词： variation law autoclave pressure leaching gas holdup mixed-flow agitator empirical equation

THEORETICAL AND EXPERIMENTAL STUDIES ON BUBBLE DIAMETER AND GAS holdup IN AERATED STIRRED TANKS

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Chinese Journal of Chemical Engineering 1996年第4期4卷 4-10页

作者：高正明王英琛施力田傅举孚北京科技大学化学工程系北京

Experiments were carried out in geometrically similar vessels with diameters of 0.287, 0.495 and 1.1m respectively. Bubble diameter distribution was measured with a dual electric conductivity probe placed in the tanks. Gas holdup was measured by spillover method. Considering the coalescence of bubbles in the upper circulation region of the aeration stirred tank, introducing the concepts of turbulence decay and effective viscosity of gas-liquid system into this work, and taking into account the equilibrium between the surface energy of the bubbles and the energy supplied by agitation, mathematical models for bubble diameter and mean gas holdup were derived. The mathematical models were confirmed by experimental data.

关键词： bubble diameter gas holdup mathematical model gas-liquid stirred tank agitated tank

Prediction of Pressure Gradient and holdup in Small Eoetvoes Number Liquid-Liquid Segregated Flow

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Chinese Journal of Chemical Engineering 2008年第2期16卷 184-191页

作者：刘夷平张华王淑华王经 Institute of Engineering Thermo-Physics School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

The segregated flow pattern, which occurs in a 26.1 mm diameter, horizontal, stainless steel test section, is investigated. Pressure gradient and in situ phase distribution data were obtained for different combinations of phase superficial velocities ranging from 0.05 m.s^-1 to 0,96 m.s^-1. For the current small Eoetvoes number liquid-liquid system （EOD=4.77）, the dominant effect of interfacial tension and wall-wetting properties of the liquids over the gravity is considered. The approach introduces the closure relationship for the case of turbulent flow m a rough pipe, and attempts to modify the two-fluid model to account for the curved interface. In present flow rates range, wave amplitudes were found small, while interfacial mixing was observed. An adjustable definition for hydraulic diame- ters of two fluids and interfacial friction factor is adopted. The predicted pressure gradient and in situ phase distribution data have been compared with present experimental data and those reported in the literature.

关键词： two-fluid model pressure gradient holdup liquid-liquid flow interfacial shear

A Model for Predicting holdup and Pressure Drop in Gas- Liquid Stratified Flow

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Chinese Journal of Chemical Engineering 2001年第1期9卷 65-69页

作者：陈永利周芳德李卫东李荣先 DepartmentofEngineeringMechanics TsinghuaUniversityBeijing100084.China StateKeyLaboratoryofMultiphaseFlowinPowerEngineeringXi＇anJiaotongUniversity Xi＇an710049China

The time-dependent liquid film thickness and pressure drop were measured by using parallel-wire conductance probes and capacitance differential-pressure transducers. Applying the eddy viscosity theory and an appropriate correlation of interfacial sear stress,a new two-dimensional separated model of holdup and pressure drop of turbulent/turbulent gas-liquid stratified flow was presented. Prediction results agreed well with experimental data.

关键词： gas-liquid two-phase flow stratified flow holdup pressure drop model

Effects of internals on phase holdup and backmixing in a slightly-expanded-bed reactor with gas–liquid concurrent upflow

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2273-2283页

作者： Kang Yu WeijieWang Tao Zhang Yumei Yong Chao Yang CAS 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 100049China 3 PetroChina Petrochemical Research InstituteBeijing 102206China

Five different internals were designed,and their effects on phase holdup and backmixing were investigated in a gas–liquid concurrent upflow reactor where the spherical alumina packing particles of three diameters(3.0,4.5 and6.0 mm)were slightly expanded under the conditions of varied superficial gas velocities(6.77×10-2-3.61×10-1 m·s-1)and superficial liquid velocities(9.47×10-4-2.17×10-3 m·s-1).The experimental results show that the gas holdup increases with the superficial gas velocity and particle size,opposite to the variational trend of liquid *** an internal component is installed amid the upflow reactor,a higher gas holdup,a less liquid holdup and a larger Peclet number characterizing the weaker backmixing are obtained compared to those in the bed without internals under the same operating ***,the minimal backmixing is observed in the reactor equipped with the internals with a novel multi-step ***,empirical correlations were proposed for estimating gas holdup,liquid holdup and Peclet number with the relative deviations within 11%,12%and 25%,respectively.

关键词： Internals Phase holdup Backmixing Slightly-expanded-bed reactor Multiphase flow Hydrodynamics

Study on the holdup and Mass Transfer Performances for Gas-Liquid-Liquid System in a Screen Plate Column

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Chinese Journal of Chemical Engineering 2001年第2期9卷 208-211页

作者：刘长厚任晓光 DepartmentofChemicalEngineering DalianUniversityofTechnologyDalian116012China DepartmentofChemicalEngineering BeijingInstituteofPetrochemicalTechnologyBeijing102600China

The gas and dispersed phase holdups and mass transfer coefficients of liquid-iquid were determined for gas-liquid-liquid three phase system in a screen plate column. The flow pattern of gas-liquid-liquid three phase system was studied under different gas velocities. The shape factors showed the geometric properties of screen plates and the corrected drop characteristic velocities were introduced. The phase holdup in two phases was correlated. The research results indicated that mass transfer coefficient for liquid-liquid system in a column with screen plates and gas agitation was found to increase apparently.

关键词： Gas-liquid-liquid systems screen plate holdup

BUBBLE SIZES AND holdup STRUCTURE IN BUBBLE COLUMNS DETERMINED BY DYNAMIC GAS DISENGAGEMENT

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Chinese Journal of Chemical Engineering 1996年第2期4卷 59-70页

作者：罗和安 Kai Hjarbo Hallvard Svendsen Department of Chemical Engineering Norwegian Institute of Technology 7034 Trondheim Norway

A new model for determining bubble size distributions in bubble columns by the dynamic gasdisengagement(DGD)technique is *** is based on an idea of non-uniform steady statedirstribution of bubble *** the axial non-uniformity,this model gives axial gasholdup *** assuming an axially homogeneous dispersion,a radial gas holdup distributioncan be *** Sauter mean diameters or specific interfacial areas for several systems areestimated by the *** results for an air-water system agree with those measured by afive-point conductivity probe *** obtained axial gas holdup distributions agree well withreported measurements and the radial gas holdup distributions are also reasonable.

关键词： bubble size gas holdup measurement dynamic gas disengagement

Gas holdups of Small and Large Bubbles in a Large-scale Bubble Column with Elevated Pressure

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Chemical Research in Chinese Universities 2004年第4期20卷 462-465页

作者： JINHai-bo YANGSuo-he ZHANGTong-wang TONGZe-min DepartmentofChemicalEngineering BeijingInstituteofPetrochemicalTechnologyBeijing102617P.R.China

Gas holdups of large bubbles and small bubbles were measured by means of dynamic gas disengagement approach in the pressured bubble column with a diameter of 0.3 m and a height of 6.6 m. The effects of superficial gas velocity, liquid surface tension, liquid viscosity and system pressure on gas holdups of small bubbles and large bubbles were investigated. The holdup of large bubbles increases and the holdup of small bubbles decreases with an increase of liquid viscosity. Meanwhile, the holdup of large bubbles decreases with increasing the system pressure. A correlation for the holdup of small bubbles was obtained from the experimental data.

关键词： Bubble column Elevated pressure Large bubble Small bubble holdup

Visual study on the characteristics of liquid and droplet in a novel rotor-stator reactor

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2643-2652页

作者： Yubin Wang Jun Li Yang Jin Ming Chen Yan Cao Jianhong Luo Department of Chemical Engineering Sichuan UniversityChengdu 610065China

Rotor–stator reactor(RSR), an efficient mass transfer enhancer, has been applied in many fields. However,the hydrodynamic characteristics of liquid flow in RSR are still a mystery despite they are fundamental for the mass transfer performance and processing capacity. In view of the above, this paper studies the liquid–liquid flow and liquid holdup in RSR under various conditions with a high-speed camera. The paper firstly demonstrates two flow patterns and liquid holdup patterns that we obtained from our experiment and then presents in succession a flow pattern and a liquid holdup criterion for the transition of film flow to filament flow and complete filling to incomplete filling. It is found that experimental parameters, including rotor–stator distance, rotational speed and volume flow rate exert great influence on the average droplet diameter and size distribution. Besides, by comparison and contrast, we also find that the experimental values match well with our previous predicted calculations of the average diameter, and the relation between the average diameter and the mean energy dissipation rate.

关键词： Rotor–stator reactor Liquid–liquid flow pattern Liquid holdup Droplet size distribution Average droplet diameter