Effect of Slag on Mixing Time in Gas-Stirred Ladles Assisted with a Physical Model

2012 ◽  
Vol 1485 ◽  
pp. 101-106 ◽  
Author(s):  
Adrián M. Amaro-Villeda ◽  
A. Conejo ◽  
Marco A. Ramírez-Argáez
Keyword(s):  
Physical Model ◽  
Mixing Time ◽  
Steel Slag ◽  
Slag Layer ◽  
Process Conditions ◽  
Steel Ladle ◽  
Phase System ◽  
Mixing Times ◽  
Two Phase ◽  
Energy Dissipated

ABSTRACTA 1/6th water physical model of a 140 tons gas-stirred steel ladle is used to evaluate mixing times (τm at 95% of chemical uniformity) in a two phase system without slag (air-water) and in a more realistic three phase system (air-water-oil) to simulate the argon-steel-slag system and quantify the effect of the slag layer on the mixing time. Slag layer is kept constant at 0.004 m. Mixing times are estimated through measured changes in pH due to the addition of a tracer (NaOH 1 M). The effect of the following variables on the mixing time is evaluated for a single injector: gas flow rate (7, 17 y 37 l/min) and the injector position (R/r= 0, 1/3, ½, 2/3 and 4/5). Experimental results obtained in this work show good agreement when compared against mixing time correlations reported by Mazumdar for the two phase air-water case (no slag considered). Another comparison is done using the new concept called “effective bath height” proposed by Barati, where the mixing time is a function of the size of the slag layer since this layer dissipates part of the total amount of stirring energy introduced into the ladle by the injection of gas. Agreement is not good in this case. Finally, an estimation of the percentage of the stirring energy dissipated by the slag is computed, including other factors that govern the dissipation of stirring energy. Percentage of energy dissipated by the slag is found to be between 2.7 to 12 % depending on the process conditions.

Experimental Study on Mixing in Gas-Stirred Ladles with and without the Slag Phase through a Water Physical Model

2012 ◽  
Vol 1373 ◽  
Author(s):  
Adrián M. Amaro-Villeda ◽  
Jorge A. González Bello ◽  
Marco A. Ramírez-Argáez.
Keyword(s):  
Physical Model ◽  
Flow Rate ◽  
Gas Flow ◽  
Mixing Time ◽  
Steel Slag ◽  
Slag Layer ◽  
Process Conditions ◽  
Steel Ladle ◽  
Gas Flow Rate ◽  
Water Gas

ABSTRACTA 1/6th gas–stirred water physical model of a 140 ton steel ladle is used to evaluate mixing in air–water and air–water–oil systems to model argon–steel and argon–steel–slag systems respectively. Thickness of the slag layer is kept constant at 0.004 m. The effect of the gas flow rate (7, 17, and 37 l/min), plug position (0, 1/3, ½, and 2/3 of the ladle radius, R), and number of plugs (1, 2, and 3) on mixing time is also analyzed in this work. Gas is injected at the bottom of the ladle under several plug configurations varying both position and number of plugs. Chemical uniformity of 95% is selected as mixing criterion. Mixing times are experimentally determined when a tracer is suddenly injected into the ladle and the model is instrumented with a pH meter to track the time evolution of the tracer concentration (NaOH 1 M solution) in a given location inside the ladle. Process conditions for best mixing in both water–gas and water-gas–slag systems are: a single plug located at 2/3 of the ladle radius with a gas flow rate of 17 l/min.

Mathematical and Physical Modeling of Three-Phase Gas-Stirred Ladles

2016 ◽  
Vol 1812 ◽  
pp. 29-34
Author(s):  
Juan A. López ◽  
Marco A. Ramírez-Argáez ◽  
Adrián M. Amaro-Villeda ◽  
Carlos González
Keyword(s):  
Mathematical Model ◽  
Physical Model ◽  
Stokes Equations ◽  
Steel Slag ◽  
Flow Patterns ◽  
Navier Stokes ◽  
Steel Ladle ◽  
Phase System ◽  
Navier Stokes Equations ◽  
Three Phase

ABSTRACTA very realistic 1:17 scale physical model of a 140-ton gas-stirred industrial steel ladle was used to evaluate flow patterns measured by Particle Image Velocimetry (PIV), considering a three-phase system (air-water-oil) to simulate the argon-steel-slag system and to quantify the effect of the slag layer on the flow patterns. The flow patterns were evaluated for a single injector located at the center of the ladle bottom with a gas flow rate of 2.85 l/min, with the presence of a slag phase with a thickness of 0.0066 m. The experimental results obtained in this work are in excellent agreement with the trends reported in the literature for these gas-stirred ladles. Additionally, a mathematical model was developed in a 2D gas-stirred ladle considering the three-phase system built in the physical model. The model was based on the Eulerian approach in which the continuity and the Navier Stokes equations are solved for each phase. Therefore, there were three continuity and six Navier-Stokes equations in the system. Additionally, turbulence in the ladle was computed by using the standard k-epsilon turbulent model. The agreement between numerical simulations and experiments was excellent with respect to velocity fields and turbulent structure, which sets the basis for future works on process analysis with the developed mathematical model, since there are only a few three-phase models reported so far in the literature to predict fluid dynamics in gas-stirred steel ladles.

scholarly journals Study on optimum technological conditions for producing androstenedione by microbial method

2019 ◽  
Vol 136 ◽  
pp. 06025
Author(s):  
Haishan SHI ◽  
Ying YANG ◽  
Weihua LI ◽  
Hui ZHANG ◽  
Xiaolei CHENG
Keyword(s):  
Substrate Concentration ◽  
Large Scale ◽  
Supply And Demand ◽  
Process Conditions ◽  
Phase System ◽  
Scale Production ◽  
Liquid Loading ◽  
Two Phase ◽  
Initial Ph ◽  
Promising Development

As an indispensable intermediate, androstenedione is widely used in drug manufacturing, especially steroidal drugs. However, the chemical manufacturing process of androstenedione is generally complicated and difficult, and it will cause serious environmental pollution in the production process. The biological method for the production of androstenedione has a very promising development prospect, because it is more economical and environmentally friendly than chemical methods. In order to better produce androstenedione on a large scale, the imbalance between supply and demand can be solved. In this study, the biaqueous phase system was used to increase the substrate concentration, and the method of transforming plant sterol by mycobacterium was used to produce androstenedione. The optimal conditions for the production of androstenedione by microbial assay were determined by orthogonal test: the aqueous two-phase system was water/ sunflower oil, the temperature was 30 °C, the initial pH was 6.5, the substrate concentration was 0.4 g/L, the rotation speed was 250 rpm, and the inoculation was carried out. The amount was 14.83%, the organic ratio was 20.65%, and the liquid loading was 150/500 mL. The preliminary production of androstenedione by microbial method has found suitable process conditions and provided data and theoretical support for its large-scale production.

scholarly journals Numerical Modeling of Equal and Differentiated Gas Injection in Ladles: Effect on Mixing Time and Slag Eye

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 917
Author(s):  
Luis E. Jardón-Pérez ◽  
Carlos González-Rivera ◽  
Marco A. Ramirez-Argaez ◽  
Abhishek Dutta
Keyword(s):  
Numerical Modeling ◽  
Numerical Model ◽  
Physical Model ◽  
Flow Rate ◽  
Gas Flow ◽  
Mixing Time ◽  
Gas Injection ◽  
Steel Slag ◽  
Gas Flow Rate ◽  
Slag Thickness

Ladle refining plays a crucial role in the steelmaking process, in which a gas stream is bubbled through molten steel to improve the rate of removal of impurities and enhance the transport phenomena that occur in a metallurgical reactor. In this study, the effect of dual gas injection using equal (50%:50%) and differentiated (75%:25%) flows was studied through numerical modeling, using computational fluid dynamics (CFD). The effect of gas flow rate and slag thickness on mixing time and slag eye area were studied numerically and compared with the physical model. The numerical model agrees with the physical model, showing that for optimal performance the ladle must be operated using differentiated flows. Although the numerical model can predict well the hydrodynamic behavior (velocity and turbulent kinetic energy) of the ladle, there is a deviation from the experimental mixing time when using both equal and differentiated gas injection at a high gas flow rate and a high slag thickness. This is probably due to the insufficient capture of the velocity field near the water–oil (steel–slag) interface and slag emulsification by the numerical model, as well as the complicated nature of correctly simulating the interaction between both gas plumes.

Study on the Role of Surfactants to Aqueous Two-Phase Synthesizing CPAM

2013 ◽  
Vol 781-784 ◽  
pp. 511-514
Author(s):  
Ya Feng Cao ◽  
Mei Jun Qu ◽  
Feng Zhi Tan ◽  
Zhao Li Liu ◽  
Yuan Li
Keyword(s):  
Monomer Conversion ◽  
Continuous Phase ◽  
Ionic Surfactants ◽  
Process Conditions ◽  
Phase System ◽  
Two Phase ◽  
Optimum Reaction ◽  
Optimum Reaction Condition ◽  
Better Than

In this paper,cationic polyacrylamide (CPAM) was synthesized by using aqueous two-phase polymerization. The Role of surfactants to aqueous two-phase synthesizing CPAM was studied, including the effect of the type,the composition and the concentration of the surfactants. The results showed that non-ionic surfactants had a better stabilizing impact on the polymer aqueous two-phase system. And the effect of the compound surfactant was better than that of a single surfactant. Take the chemical compound of Tween80 and OP10 as the polymerization auxiliaries, the optimum reaction condition of synthesis were as follows:wTween80:ѡOP10=1.5,w=1.6%, 50°C.In this process conditions, the distribution coefficient was the most appropriate in the continuous phase, the total monomer conversion rate and the intrinsic viscosity number of the product reached the maximum.

Chiral separation of α-cyclohexylmandelic acid enantiomers using ionic liquid/salt aqueous two-phase system

2015 ◽  
Vol 69 (11) ◽  
Author(s):  
Lei-Lei Chen ◽  
Fen-Fang Li ◽  
Zhi-Jian Tan
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Chiral Separation ◽  
Mixing Time ◽  
Chiral Selector ◽  
Phase System ◽  
Two Phase ◽  
Aqueous Two Phase System ◽  
Liquid Salt ◽  
Influencing Parameters

AbstractIn this paper, an ionic liquid-based aqueous two-phase system (ILATPS) was applied to the chiral separation of α-cyclohexylmandelic acid (α-CHMA) enantiomers with hydroxypropyl-β- cyclodextrin (HP-β-CD) as the chiral selector. Several influencing parameters were investigated including the types and concentration of ionic liquids, the amount of phase-forming salt, temperature, mixing time, pH, and the content of HP-β-CD. The results showed that not all ILATPS had the ability to chirally recognise the selected enantiomers and that [C

Aqueous Two-Phase System in the Synthesis of Starch Graft Acrylamide Polymer

2014 ◽  
Vol 672-674 ◽  
pp. 734-736 ◽  
Author(s):  
Meng Zheng ◽  
Ling Xun Liang
Keyword(s):  
Base Material ◽  
Monomer Concentration ◽  
Monomer Conversion ◽  
Raw Material ◽  
Polymerization Reaction ◽  
Optimum Process ◽  
Process Conditions ◽  
Phase System ◽  
Two Phase ◽  
Aqueous Two Phase System

With starch as base material, acrylamide (AM) as raw material, polyethylene glycol (PEG20000) as dispersing medium, in aqueous two-phase system synthesized starch grafting acrylamide polymer. Through the indoor experiment, determine the optimum process conditions of polymerization reaction, the initial monomer concentration was 15%, PEG20000 concentration of 10%, m (ST) : m (AM) = 3:7, dosage of initiator is 0.1%, T = 50 °C, T = 6 h. Get monomer conversion was 98.5%, the characteristic viscosity.methods according to 761.5 mg/L of graft copolymerization. Of product have been characterized through infrared spectrum and analysis.

scholarly journals Numerical Modeling of Open-Eye Formation and Mixing Time in Argon Stirred Industrial Ladle

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 829 ◽  
Author(s):  
Eshwar Kumar Ramasetti ◽  
Ville-Valtteri Visuri ◽  
Petri Sulasalmi ◽  
Timo Fabritius ◽  
Tommi Saatio ◽  
...  
Keyword(s):  
Flow Rate ◽  
Molten Steel ◽  
Gas Flow ◽  
Transport Model ◽  
Mixing Time ◽  
Steel Slag ◽  
Slag Layer ◽  
Metal Bath ◽  
Argon Gas ◽  
Eye Size

In secondary metallurgy, argon gas stirring and alloying of elements are very important in determining the quality of steel. Argon gas is injected through the nozzle located at the bottom of the ladle into the molten steel bath; this gas breaks up into gas bubbles, rising upwards and breaking the slag layer at high gas flow rates, creating an open-eye. Alloy elements are added to the molten steel through the open-eye to attain the desired steel composition. In this work, experiments were conducted to investigate the effect of argon gas flow rate on the open-eye size and mixing time. An Eulerian volume of fluid (VOF) approach was employed to simulate the argon/steel/slag interface in the ladle, while a species transport model was used to calculate the mixing time of the nickel alloy. The simulation results showed that the time-averaged value of the open-eye area changed from 0.66 to 2.36 m2 when the flow rate of argon was varied from 100 to 500 NL/min. The mixing time (95% criterion) of tracer addition into the metal bath decreased from 139 s to 96 s, when the argon flow rate was increased from 100 to 500 NL/min. The model validation was verified by comparing with measured experimental results.

Impedance spectroscopy of BaTiO3 cubes suspended in lossy liquids as a physical model of two-phase system

2010 ◽  
Vol 108 (7) ◽  
pp. 074111 ◽  
Author(s):  
Piotr Jasinski ◽  
Vladimir Petrovsky ◽  
Fatih Dogan
Keyword(s):  
Impedance Spectroscopy ◽  
Physical Model ◽  
Phase System ◽  
Two Phase
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