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.

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).

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.

Modeling evaluation on solid-liquid mixing characteristics in a dislocated guide impeller stirred tank

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Deyin Gu ◽  
Fenghui Zhao ◽  
Xingmin Wang ◽  
Zuohua Liu
Keyword(s):  
Power Consumption ◽  
Solid Particle ◽  
Particle Diameter ◽  
Solid Particles ◽  
Stirred Tank ◽  
Mixing Process ◽  
Solid Holdup ◽  
Aperture Ratio ◽  
Liquid Mixing ◽  
Solid Liquid

Abstract The solid-liquid mixing characteristics in a stirred tank with pitched blade impellers, dislocated impellers, and dislocated guide impellers were investigated through using CFD simulation. The effects of impeller speed, impeller type, aperture ratio, aperture length, solid particle diameter and initial solid holdup on the homogeneity degree in the solid-liquid mixing process were investigated. As expected, the solid particle suspension quality was increased with an increase in impeller speed. The dislocated impeller could reduce the accumulation of solid particles and improve the cloud height compared with pitched blade impeller under the same power consumption. The dislocated guide impeller could enhance the solid particles suspension quality on the basis of dislocated impeller, and the optimum aperture ratio and aperture length of dislocated guide impeller were 12.25% and 7 mm, respectively, in the solid-liquid mixing process. Smaller solid particle diameter and lower initial solid holdup led to higher homogeneity degree of solid-liquid mixing system. The dislocated guide impeller could increase solid particle integrated velocity and enhance turbulent intensity of solid-liquid two-phase compared with pitched blade impeller and dislocated impeller under the same power consumption.

scholarly journals Scale-Up of Solid-Liquid Mixing Based on Constant Power/Volume and Equal Blend Time Using VisiMix Simulation

2018 ◽  
Vol 187 ◽  
pp. 04002
Author(s):  
Megawati ◽  
Bayu Triwibowo ◽  
Karwono ◽  
Waliyuddin Sammadikun ◽  
Rofiatun Musfiroh
Keyword(s):  
Solid Phase ◽  
Scale Up ◽  
Solid Particles ◽  
Liquid Mixing ◽  
Liquid Suspension ◽  
Two Parameters ◽  
Solid Liquid ◽  
Tank Geometry ◽  
Impeller Geometry

Mixing is one of the important process in many areas of chemical industries, for instance pharmaceutical, drug, ink, paint and other industries. Solid-liquid suspension is produced for 80% of all mixing industries such as leaching process, crystallization process, catalytic reactions, precipitation, coagulation, dissolution and other applications. Two main objectives in solid-liquid mixing namely, avoid settling of solid particles on the tank bottom and ensure the solid particles are uniformly distributed. Many factors that can affect the quality of solid-liquid mixing, they are tank geometry, impeller geometry and speed, baffles, viscosity and density of media. Scale-up of the process is important to conduct before produce it on commercial scale. Two parameters for scale-up solid-liquid mixing are equal blend time and power per volume. Before scaling up the process to industrial scale, an engineer must know the condition of the mixture between both of two. VisiMix can simulating scale-up of solid-liquid mixing in order to know the phenomena inside the tank without conducting a large number of experiments and cheaper. The simulation start from keep the ratio of impeller to tank diameter remains constant, then change the condition operation of mixing. In this paper, power per volume parameter is more recommended as a result of the degree of uniformity of solid phase in liquid.

scholarly journals Solid-liquid equilibrium in liquid compound fertilizers

2018 ◽  
Vol 24 (1) ◽  
pp. 59-68
Author(s):  
Kristina Jancaitienė ◽  
Rasa Slinksienė
Keyword(s):  
Crystallization Temperature ◽  
High Speed ◽  
Solid Phase ◽  
Nitrogen Concentration ◽  
Multicomponent System ◽  
Liquid System ◽  
Insoluble Residue ◽  
Aqueous Salt Solutions ◽  
Calcium Magnesium ◽  
Solid Liquid

Liquid compound fertilizers (LCF) are aqueous salt solutions which nourish the soil. They contain nitrogen, phosphorus, potassium, sometimes calcium, magnesium and micronutrients. An LCF solution has practically no insoluble residue and contains the elements in a fully digestible form and is a high-speed, highly effective fertilizer. It is important to assess the equilibrium in the solid-liquid system when creating liquid compound fertilizers, since their basic properties, concentration and crystallization temperature, depend on it. The aim of the study was to determine properties of a liquid multicomponent (K+, NH4 +, Cl- and PO4 3-) system. This liquid multicomponent system, which was obtained as a by-product in the conversion of KCl and NH4H2PO4, can be used as a liquid fertilizer. This work investigates liquid fertilizers? chemical composition and their physicochemical properties, such as crystallization temperature, pH, density, viscosity and corrosivity. In order to increase nitrogen concentration, ammonium nitrate was added. Composition of the solid phase obtained by crystallization was identified by methods of chemical and instrumental analysis (radiography, infrared molecular absorption spectroscopy and optical microscopy). The results show that all properties of liquid fertilizers are best when the concentration of NH4NO3 in liquid solutions equals 8%.

Stochastic model of the flow mechanically stirred solid-liquid system

1980 ◽  
Vol 45 (7) ◽  
pp. 2070-2084 ◽  
Author(s):  
Vladimír Kudrna ◽  
Václav Machoň ◽  
Vlasta Hudcová
Keyword(s):  
Diffusion Equation ◽  
Stochastic Model ◽  
Boundary Conditions ◽  
Stationary State ◽  
Flow System ◽  
Solid Phase ◽  
Liquid System ◽  
Ideal Mixing ◽  
Phase Liquid ◽  
Solid Liquid

An attempt is made to describe by use of the onedimensional stochastic model the flow system solid phase-liquid stirred by the mechanical rotary mixer. At the assumption that the solid phase is dimensionally homogenous a diffusion equation has been obtained which is solved under the boundary conditions, characterizing the method of withdrawal of the solid phase from the system. It is demonstrated that the model can express also the relations usually used for description of similar situations (ideal mixing, separation coefficients in stationary state etc.) like individual cases.

Turbulent Solid-Liquid Two-Phase Flow Simulation With Turbulence Intensity and Time Scale Model

2009 ◽  
Author(s):  
Z. Mansoori ◽  
M. Saffar-Avval ◽  
B. Nojabaii ◽  
F. Behzad ◽  
G. Ahmadi
Keyword(s):  
Time Scale ◽  
Model Comparison ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Solid Particles ◽  
Scale Model ◽  
Particle Collision ◽  
Phase Flow ◽  
Two Phase ◽  
Solid Liquid

Two-dimensional simulation of turbulent solid-liquid flow is carried out. The modeling is established for a two-phase flow of solid particles in a vertical pipe water flow. Governing equations of flow and turbulence field are solved in an Eulerian-Lagrangian approach by the use of k-τ (turbulence time scale) model and trajectories of the particles are obtained using the Lagrangian method with a deterministic inter-particle collision model. Comparison between the results of the model for mean and r.m.s velocities of the liquid and solid phase with the experimental results shows a good agreement. The effect of variation of particle density and concentration are studied.

scholarly journals Peloids as Thermotherapeutic Agents

2021 ◽  
Vol 18 (4) ◽  
pp. 1965 ◽  
Author(s):  
Francisco Maraver ◽  
Francisco Armijo ◽  
Miguel Angel Fernandez-Toran ◽  
Onica Armijo ◽  
Jose Manuel Ejeda ◽  
...  
Keyword(s):  
Solid Phase ◽  
Raw Materials ◽  
Liquid System ◽  
Mineral Waters ◽  
Heat Flow Rate ◽  
Psoriatic Arthropathy ◽  
Reduction Of Pain ◽  
Solid Liquid ◽  
Main Effects

The use of peloids as heat-providing therapeutic systems dates back to antiquity. Such systems consist of a liquid phase and an organic or inorganic solid phase. The latter facilitates the handling, preparation and stability of the solid–liquid system, modifying its organoleptic and phy-sicochemical properties, and improves its efficacy and tolerance. Peloids enable the application of heat to very specific zones and the release of heat at a given rate. The aims of this work are to study 16 reference peloids used in medical spa centers as thermo-therapeutic agents as well as to propose nine raw materials as a solid phase for the preparation of peloids. The physical properties studied are the centesimal composition, the instrumental texture and the thermal parameters. In conclusion, the peloids of the medical spas studied are used as thermotherapeutic agents in the treatment of musculoskeletal disorders, especially in knee osteoarthritis and to a lesser extent in back pain and psoriatic arthropathy. The clinical experience in these centers shows that the main effects of the application of their peloids are the reduction of pain, an increase in the joint’s functional capacity and an improvement in the quality of life. As thermotherapeutic agents, all the peloids of the me-dical spas studied and the pastes (raw materials with distilled water) examined showed a heat flow rate of up to four times lower than that shown by the same amount of water. The raw materials studied can be used as solid phases for the preparation of peloids with mineral waters.

scholarly journals Computational fluid dynamics simulation of solid-liquid suspension characteristics in a stirred tank with punched circle package impellers

2020 ◽  
Vol 18 (9) ◽  
Author(s):  
Deyin Gu ◽  
Mei Ye ◽  
Zuohua Liu
Keyword(s):  
Fluid Dynamics ◽  
Power Consumption ◽  
Solid Particle ◽  
Particle Diameter ◽  
Solid Particles ◽  
Stirred Tank ◽  
Impeller Speed ◽  
Particle Suspension ◽  
Liquid Suspension ◽  
Solid Liquid

AbstractSolid-liquid suspension characteristics in a stirred tank with four pitched-blade impellers, circle package impellers, and punched circle package impellers were studied via computational fluid dynamics (CFD) simulation. A classical Eulerian-Eulerian approach coupled with the standard k-ε turbulence model was adopted to simulate the solid-liquid two-phase turbulent flow. The effects of impeller speed, power consumption, impeller type, aperture size/ratio, solid particle diameter and liquid viscosity on the solid particle suspension quality were investigated. Results showed that the solid particle suspension quality was improved with an increment in the impeller speed. Punched circle package impeller could reduce the just suspension speed and improve the level of homogeneity for solid-liquid mixing process on the basis of four pitched-blade impeller and circle package impeller. The optimum aperture ratio and aperture diameter were 11.8% and 8 mm, respectively, for solid particles suspension process in this work. Smaller particle diameter led to smaller settling velocity and higher solid particle suspension quality. More viscous liquid was easier for sustaining the solid particles in suspension state. Meanwhile, punched circle package impeller can reduce the power consumption compared with four pitched-blade impeller and circle package impeller at the same impeller speed, and enhance the solid integrated velocity, turbulent kinetic energy, and turbulent kinetic energy dissipation rate of solid-liquid mixing system at the same power consumption.

scholarly journals Dynamics and Wear Analysis of Hydraulic Turbines in Solid-liquid Two-phase Flow

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 790-796 ◽  
Author(s):  
Liying Wang ◽  
Bingyao Li ◽  
Weiguo Zhao
Keyword(s):  
Two Phase Flow ◽  
Solid Phase ◽  
Guide Vane ◽  
Hydraulic Turbine ◽  
Solid Particles ◽  
Particle Model ◽  
Volume Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Solid Liquid

Abstract To solve unstable operating and serious wearing of a hydraulic turbine in its overflow parts under solid-liquid two-phase flow, a particle model software and an inhomogeneous model in CFX are used to simulate the hydraulic turbine to understand the wearing of overflow parts and the external characteristics under the solid-liquid two-phase flow. Eleven different conditions at different densities and concentration have been calculated. The simulation results show that the volume distribution of solid particles is larger at the turn of the volute and nose end, resulting in the serious wear in this area. Due to uniform flow at the butterfly edge of volute under solid-liquid two-phase flow, the wear at the entrance of guide vane, the inlet of the blade and the outlet in the shroud is more serious than in other sections. Meanwhile, the collision between the solid phase particles and the overflow components is more intense under solid-liquid two-phase flow in the rotor which can lead to cavitation especially in the outlet and shroud of the blade. In addition, with the increase of density and concentration of solid particles the inlet and outlet pressure difference gradually rises, causing the efficiency loss of the hydraulic turbine.

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