Experimental analysis of the hydrodynamics of a three-phase system in a vessel with two impellers

2012 ◽  
Vol 66 (6) ◽  
Author(s):  
Anna Kiełbus-Rąpała ◽  
Joanna Karcz
Keyword(s):  
Experimental Analysis ◽  
Gas Flow ◽  
Gas Bubbles ◽  
Liquid System ◽  
Internal Diameter ◽  
Phase System ◽  
Gas Dispersion ◽  
Rushton Turbine ◽  
Three Phase ◽  
Solid Liquid

AbstractResults of experimental analysis concerning gas hold-up and average residence time of gas bubbles in a three-phase gas-solid-liquid system produced in a baffled, double-impeller vessel are presented. Measurements were carried out in a vessel with the internal diameter of 0.288 m. Two different double-impeller configurations were used for agitation: Rushton turbine (lower) — A 315 (upper) and Rushton turbine (lower) — HE 3 (upper). Upper impellers differed in the fluid pumping mode. Coalescing and non-coalescing systems were tested. Liquid phases were distilled water (coalescing system) and aqueous solutions of NaCl (non-coalescing systems). The ability of gas bubbles to coalesce in the liquid was described using parameter Y. Dispersed phases were air and particles of sea sand. The experiments were conducted at seven different gas flow rates and two particle loadings. Effects of the ability of gas bubbles to coalesce (liquid phase properties), operating parameters (superficial gas velocity, impeller speed, solids loadings), and of the type of the impeller configuration on the investigated parameters were determined. The results were approximated mathematically. For both impeller configurations tested, significantly higher gas hold-up values were obtained in the non-coalescing gas-solid-liquid systems compared to the coalescing one. Out of the tested impeller systems, the RT-A 315 configuration proved to have better performance ensuring good gas dispersion in the liquid in the three-phase systems.

Agitation of a gas-solid-liquid system in a vessel with high-speed impeller and vertical tubular coil

2012 ◽  
Vol 66 (6) ◽  
Author(s):  
Marta Major-Godlewska ◽  
Joanna Karcz
Keyword(s):  
Power Consumption ◽  
High Speed ◽  
Gas Bubbles ◽  
Liquid System ◽  
Specific Power ◽  
Specific Power Consumption ◽  
Rushton Turbine ◽  
Agitated Vessel ◽  
Solids Concentration ◽  
Solid Liquid

AbstractExperimental results of gas hold-up, power consumption and residence time of gas bubbles in a gas-solid-liquid system produced in an agitated vessel equipped with a high-speed impeller and a vertical tubular coil are presented in this paper. Critical agitator speed, needed for the dispersion of gas bubbles and solid particles in liquid were also identified. The studies were carried out in an agitated vessel of the inner diameter D = 0.634 m and the working liquid volume of about 0.2 m3. A tubular coil of the diameter of 0.7D, consisting of 24 vertical tubes of the diameter of 0.016D, was located inside the flat-bottomed vessel. The agitated vessel was equipped with a Rushton turbine with six blades or an A 315 impeller with four blades. Both impellers had diameter, d, equal to 0.33D. The vessel was filled with liquid up to the height H = D. In this study, air and particles of sea sand with the mean diameter of 335 μm and the concentration of up to 3.0 mass % were dispersed in distilled water as the liquid phase. The measurements were carried out within the turbulent regime of the fluid flow in the agitated vessel. Results of the measurements were processed graphically and mathematically. Lower values of the critical agitator speed, n JSG, needed for simultaneous dispersion of gas bubbles and particles with the solids concentration from 0.5 mass % to 2 mass %, were obtained for the vessel equipped with the A 315 impeller. Higher values of the specific power consumption were reached for the vessel with the Rushton turbine. Higher values of the gas hold-up and residence time of the gas bubbles in the fluid were obtained for the system equipped with the Rushton turbine. Results of the gas hold-up as a function of the specific power consumption, superficial gas velocity and solids concentration were approximated with good accuracy using Eq. (5).

scholarly journals Estimating Just Suspension Speed for Stirred Reactors Using Power Measurement

2019 ◽  
Vol 2 ◽  
pp. 1-5
Author(s):  
Raja Shazrin Shah Raja Ehsan Shah ◽  
Baharak Sajjadi ◽  
Abdul Aziz Abdul Raman ◽  
Tiam You See ◽  
Shaliza Ibrahim ◽  
...  
Keyword(s):  
Power Consumption ◽  
Solid Phase ◽  
Liquid System ◽  
Solid Particles ◽  
Power Measurement ◽  
Internal Diameter ◽  
Rushton Turbine ◽  
Suspend Solid ◽  
Experimental Values ◽  
Solid Liquid

A simplified mathematical model was developed to predict the just suspended speed, NJS in a solid-liquid system by analyzing the net impeller power consumption to suspend solid particles. A fully baffled tank with an internal diameter of 400mm equipped with a standard Rushton turbine with a diameter of D=T/3 (133mm) was used in this work. Glass beads were used as the solid phase and distilled water was used as the liquid phase. Solid loadings were varied within the range of 0-27 wt%. Power consumption was measured using the shaft torque method. The predicted NJS values were in a good approximation to the experimental values using the Zwietering’s criterion with a deviation of 2 – 10%. The deviation was lower for higher solid concentrations.

Generalized Young Equation for Cylindrical Droplets within a Homogeneous and Smooth Regular Triangular Prism Filled with Gas in Three Convex Corners

2016 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Long Zhou ◽  
Guang-Hua Sun ◽  
Ai-Jun Hu ◽  
Xiao-Song Wang
Keyword(s):  
Line Tension ◽  
Phase System ◽  
Triangular Prism ◽  
Gas Phases ◽  
Three Phase ◽  
Dividing Surface ◽  
Solid Liquid ◽  
Wetting Behaviors ◽  
Young Equation ◽  
Dividing Line

<p class="1Body">Based on the approaches of Gibbs’s dividing surface and Rusanov’s dividing line, the wetting behaviors of cylindrical droplets that at equilibrium are sitting inside a homogeneous and smooth regular triangular prism filled with gas in three convex corners are studied. For the three-phase system, which is composed of solid, liquid and gas phases, a generalized Young equation for cylindrical drops in a homogeneous and smooth regular triangular prism imbued with gas within three apex corners has been successfully derived including the effects of the line tension.</p>

Évaluation du pouvoir adhérant du Lactobacillus helveticus au polystyrène expansé

1992 ◽  
Vol 38 (7) ◽  
pp. 672-675 ◽  
Author(s):  
Nathalie Dion ◽  
Jacques Goulet ◽  
Patrick Boyaval
Keyword(s):  
Surface Tension ◽  
Liquid System ◽  
Contact Angles ◽  
Expanded Polystyrene ◽  
Lactobacillus Helveticus ◽  
Bacterial Cells ◽  
Three Phase ◽  
Thermodynamic Conditions ◽  
Polystyrene Support ◽  
Solid Liquid

We measured the surface tension of a three-phase (solid–solid–liquid) system consisting of the bacterium Lactobacillus helveticus in a culture medium containing an expanded polystyrene support, to determine the adherence capacity of the bacteria to the support. The surface tension of the expanded polystyrene and the L. helveticus cells was evaluated by measuring contact angles. The Wilhelmy's microslide method was used to measure the surface tension of the liquid phase. The values obtained showed that the adherence capacity of the L. helveticus cells to expanded polystyrene pellets was not facilitated under the experimental thermodynamic conditions. The pellet surfaces and adhering bacterial cells were examined with a scanning electron microscope. The pellets exhibited several grooves in which microbial cells preferentially accumulated. Key words: Lactobacillus helveticus, adherence, surface tension, expanded polystyrene. [Translated by the journal]

An Optical Method for Determining Bubble Size Distributions—Part II: Application to Bubble Size Measurement in a Three-Phase Fluidized Bed

1988 ◽  
Vol 110 (3) ◽  
pp. 332-338 ◽  
Author(s):  
P. R. Meernik ◽  
M. C. Yuen
Keyword(s):  
Bubble Size ◽  
Gas Flow ◽  
Phase System ◽  
Size Distributions ◽  
Size Measurement ◽  
Flow Conditions ◽  
Gas Fluxes ◽  
Three Phase ◽  
Beam Technique ◽  
Eotvos Number

The light beam technique, described in Part I of a paper with the same title, was applied to a three-phase system (nitrogen, organic solvents, and glass particles) to study the equilibrium bubble size distributions. A range of liquid and gas flow rates, with respective superficial velocities of 1–8 cm/sec and 0.1–1.1 cm/s; and various particles, 2 mm diameter by 5 mm long cylinders and 1 to 5 mm diameter spheres, were considered. Typical average bubble diameters were measured to be in the range of 1.2 to 2 mm. For the range of flow conditions considered, the Sauter mean diameters, normalized by particle size, were found to be proportional to the Eotvos number and essentially independent of the liquid and gas fluxes.

Application of CFD Modelling Technique in Engineering Calculations of Three-Phase Flow Hydrodynamics in a Jet-Loop Reactor

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Roman G. Szafran ◽  
Andrzej Kmiec
Keyword(s):  
Control Volume ◽  
Turbulence Models ◽  
Liquid System ◽  
Circulation Rate ◽  
Phase System ◽  
Cfd Modelling ◽  
Loop Reactor ◽  
Three Phase ◽  
Three Phase Flow ◽  
Solid System

The hydrodynamics of a down flow jet-loop reactor with a gas-liquid-solid three-phase system in semi-industrial scale were investigated. The Eulerian-Eulerian modelling approach was applied to predict flow behaviour in the reactor. A commercially available, control-volume-based code FLUENT 6.1 was chosen to carry out the computer simulations. In order to reduce computational times and required system resources, the 2D axisymmetric segregated solver was chosen. The influence of different k-e turbulence models, as well as, different types of meshes on velocity profiles in each phase was analyzed. The unstructured mesh reduces discrepancies on the axis of symmetry caused by the axisymmetric solver and is more accurate. The prediction error of the water circulation rate ratio for a gas-liquid system was only 3.6 % and about 15 % for gas-liquid-solid system. Unfortunately the gas hold-up was not predicted properly.

scholarly journals Determining the Effective Mass Transfer Area in Three-Phase Fluidized Bed with Low Density Inert Solids

2019 ◽  
Vol 70 (11) ◽  
pp. 4040-4046
Author(s):  
Simion Dragan
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Effective Mass ◽  
Fluidized Bed ◽  
Internal Diameter ◽  
Gas Velocity ◽  
Mathematical Correlation ◽  
Liquid Load ◽  
Three Phase ◽  
Solid Liquid

The absorption process is strongly influenced by the effective mass transfer area. In this study the effective mass transfer area in gas-solid-liquid three-phase fluidized bed was determined, in a fluidizing column having an internal diameter of 0.14 m and a height of 1.10 m. The solid packing is made of plastic hollow spheres of 0.01 m diameter, with 415 m2/m3 geometric area and a density of 170 Kg/m3. The absorption of carbon dioxide from the air-carbon dioxide mixture with molar concentration of 0.05M, 0.08M and 0.1M CO2 into sodium hydroxide aqueous solutions of 0.5N and 1.0 N has been employed as test reaction. The experiments were conducted with liquid load changing from 6.49 to 16.24 m�/(m� h) and gas velocity of 1.1 m/s and 2.1 m/s. It was found that the effective mass transfer area increased both with the increase of the gas velocity and the increase of the liquid spray density. It has been observed that the effective mass transfer area in gas-solid-liquid three-phase fluidized bed absorber is from three to eight times higher than the geometric area of the solid packing. A mathematical correlation has been established in order to predict the effective mass transfer area,under the specified conditions, with a deviation of less than 5%.

scholarly journals Influence of fluid-mechanical characteristics of the system on the volumetric mass transfer coefficient and gas dispersion in three-phase system

2014 ◽  
Vol 68 (4) ◽  
pp. 483-490
Author(s):  
Milena Knezevic ◽  
Dragan Povrenovic
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Solid Particles ◽  
Phase System ◽  
Volumetric Mass Transfer Coefficient ◽  
Gas Dispersion ◽  
Operation Conditions ◽  
Three Phase ◽  
Different Types

Distribution of gas bubbles and volumetric mass transfer coefficient, Kla, in a three phase system, with different types of solid particles at different operation conditions were studied in this paper. The ranges of superficial gas and liquid velocities used in this study were 0,03-0,09 m/s and 0-0,1 m/s, respectively. The three different types of solid particles were used as a bed in the column (glass dp=3 mm, dp=6 mm; ceramic dp=6 mm). The experiments were carried out in a 2D plexiglas column, 278 x 20,4 x 500 mm and in a cylindrical plexiglas column, with a diameter of 64 mm and a hight of 2000 mm. The Kla coefficient increased with gas and liquid velocities. Results showed that the volumetric mass transfer coefficient has a higher values in three phase system, with solid particles, compared with two phase system. The particles properties (diameter and density) have a major impact on oxygen mass transfer in three phase systems.

scholarly journals Thermodynamics of phase equilibrium in solid-liquid and solid-gas systems

2021 ◽  
Vol 83 (1) ◽  
pp. 30-35
Author(s):  
Y. I. Shishatskii ◽  
A. A. Derkanosova ◽  
S. A. Tolstov
Keyword(s):  
Driving Force ◽  
Cheese Whey ◽  
Extraction Process ◽  
Liquid System ◽  
Average Concentration ◽  
Phase System ◽  
Gibbs Equation ◽  
Two Phase ◽  
Thermodynamic Potentials ◽  
Solid Liquid

The thermodynamic equilibrium of a two-phase system is described by the Gibbs equation, which includes state parameters. On the basis of the Gibbs equation and the combined equation of the first and second laws of thermodynamics, thermodynamic potentials are written: internal energy, enthalpy and Gibbs free energy. If the two phases are in equilibrium, then the temperatures, pressures and chemical potentials of these phases are equal to each other. Equalities express the conditions of thermal and mechanical equilibrium, as well as the condition for the absence of a driving force for the transfer of a component across the interface. For a two-phase system, the Gibbs-Duhem equation connects the volume and entropy of 1 mole of the mixture, the content of any component, expressed in mole fractions. Extraction from lupine particles with cheese whey (solid-liquid system) is considered. The driving force of the extraction process in the solid-liquid system is the difference between the concentration of the solvent at the surface of the solid C and its average concentration C0 in the bulk of the solution. The concentration at the interface is usually taken to be equal to the concentration of a saturated solution of Cn, since equilibrium is established rather quickly near the surface of a solid. Then the driving force of the process is expressed as Cn – C0. A curve for the extraction of extractives from lupine with cheese whey was plotted by superimposing low-frequency mechanical vibrations.

scholarly journals Experimental analysis of gas hold-up for gas-liquid system agitated in a vessel equipped with two impellers and vertical tubular baffles

2018 ◽  
Vol 20 (1) ◽  
pp. 7-12
Author(s):  
Marta Major-Godlewska ◽  
Dawid Radecki
Keyword(s):  
Experimental Analysis ◽  
High Speed ◽  
Gas Bubbles ◽  
Liquid System ◽  
Gas Holdup ◽  
Graphic Form ◽  
Liquid Systems

Abstract The influence of impellers system and type of liquid on the gas hold-up in the vessel has been presented in this paper. The analysis of gas hold-up was conducted on the basis of the data obtained in the vessel of the diameter D = 0.288 m, where the vessel was filled by a liquid up to the height H = 2D. The vessel was equipped in 24 vertical tubular baffles located on the circuit and two high-speed impellers situated on a shaft. Five different configurations of high-speed impellers were employed. The experiments in the gas-liquid system were conducted for setups which differed in capability of gas bubbles coalescence. The results of the experiment of the gas holdup for the five impellers configurations and four gas-liquid systems were presented in the graphic form and they were described mathematically.

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