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.

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.

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.

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.

A Study on the Effect of Process Parameters on Surface Topography of Al Thin Films on Various Substrates Using AFM

2011 ◽  
Vol 383-390 ◽  
pp. 903-908
Author(s):  
S. Shanmugan ◽  
D. Mutharasu ◽  
Z. Hassan ◽  
H. Abu. Hassan
Keyword(s):  
Thin Films ◽  
Surface Topography ◽  
Flow Rate ◽  
Gas Flow ◽  
Process Conditions ◽  
Gas Flow Rate ◽  
Glass Substrates ◽  
Sputtering Power ◽  
Large Particles ◽  
Ar Gas

Al thin films were prepared over different substrates at various process conditions using DC sputtering. The surface topography of all prepared films was examined using AFM technique. Very smooth, uniform and dense surface were observed for Al films coated over Glass substrates. The observed particle size was nano scale (20 -70 nm) for Glass substrates. Sputtering power showed immense effect on surface roughness with respective to Ar gas flow rate. Noticeable change on surface with large particles was observed in Copper substrates at various sputtering power and gas flow rate.

scholarly journals Effect of Differentiated Injection Ratio, Gas Flow Rate, and Slag Thickness on Mixing Time and Open Eye Area in Gas-Stirred Ladle Assisted by Physical Modeling

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 555 ◽  
Author(s):  
Luis E. Jardón-Pérez ◽  
Daniel R. González-Morales ◽  
Gerardo Trápaga ◽  
Carlos González-Rivera ◽  
Marco A. Ramírez-Argáez
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Mixing Time ◽  
Flow Ratio ◽  
Gas Flow Rate ◽  
Nsga Ii ◽  
Image Velocimetry ◽  
Gas Flow Ratio ◽  
Slag Thickness ◽  
Injection Ratio

In this work, the effects of equal (50%/50%) or differentiated (75%/25%) gas flow ratio, gas flow rate, and slag thickness on mixing time and open eye area were studied in a physical model of a gas stirred ladle with dual plugs separated by an angle of 180°. The effect of the variables under study was determined using a two-level factorial design. Particle image velocimetry (PIV) was used to establish, through the analysis of the flow patterns and turbulence kinetic energy contours, the effect of the studied variables on the hydrodynamics of the system. Results revealed that differentiated injection ratio significantly changes the flow structure and greatly influences the behavior of the system regarding mixing time and open eye area. The Pareto front of the optimized results on both mixing time and open eye area was obtained through a multi-objective optimization using a genetic algorithm (NSGA-II). The results are conclusive in that the ladle must be operated using differentiated flow ratio for optimal performance.

scholarly journals FEATURES FORMATION ZONE OF WAVES AND BURSTS ON THE SURFACE LADLE BATH

2021 ◽  
Vol 2 (39) ◽  
pp. 7-15
Author(s):  
Е. Sigarev ◽  
G. Kryachko ◽  
A. Dovzhenko ◽  
Yu. Lobanov ◽  
A. Pohvalitiy
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Slag Layer ◽  
Gas Flow Rate ◽  
Improve Design ◽  
Free Zone ◽  
Neutral Gas ◽  
Temperature Modeling ◽  
Slag Thickness ◽  
Submerged Lance

The results studies influence physicochemical properties and thickness cover slag, formed during ladle desulfurization pig iron by blowing a mixture of lime and magnesium, features formation a breaker on the surface bath and the level of metal losses with emissions outside ladle from this zone are presented. The necessity creating conditions for ensuring height breaker, which would not exceed thickness slag layer on the surface bath, has been substantiated. Using results of the high-temperature simulation blowing the cast iron melt with a neutral gas supplied through the nozzles tips stationary and rotating submersible lances, features development of counter waves and metal splashes in the absence and during formation slag cover with thickness of 30—80 mm on the surface bath are determined. The features change in the height and area breakers are determined depending on the gas flow rate for blowing bath and thickness slag. Based on the analysis results low-temperature modeling bath blowing, scientific ideas about the combined effect of the bath blowing intensity, speed of rotation submerged lance and thickness slag layer on the diameter bubbling zone, gas saturation of the bath and features wave formation on its surface in the slag-free zone were further developed (so-called «eye»). The nature relationship between length of the gas jet from lance nozzle, diameter «eye», and geometric parameters breaker has been established. It is shown that dependence profile breaker on speed of rotation lance and thickness slag layer is nonlinear. So, blowing bath through tip of a rotating lance with one nozzle at 240 rpm. with a gas flow rate of 2.2 l/min. creates conditions for raising top breaker to a height that is 33 % higher than the current thickness slag layer and contributes to the intensification formation of waves and bursts on the surface bath. With a decrease in the gas flow rate to 1.0 l/min., Under other unchanged conditions, height breaker is already 2/3 of the height slag layer, and as thickness slag decreases proportionally decreases. The smallest, recorded in the experiments, relative height breaker was 33.3% of the slag thickness at a lance rotation speed in the range of 90—120 rpm. Mathematical models are proposed that are suitable for calculating height breakers depending on the thickness slag layer, speed of rotation lance and intensity of gas injection into the bath. Taking into account established mutually opposite effect thickness of the cover slag layer and speed of rotation submerged lance on the «eye» area and height of the breaker, it is advisable to continue search for ways to improve design tip submerged lance and slag mode of ladle desulfurization.

Mixing of Fluids in Tanks by Gas Bubble Plumes

1987 ◽  
Vol 109 (2) ◽  
pp. 186-193 ◽  
Author(s):  
A. M. Godon ◽  
J. H. Milgram
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Mixing Time ◽  
Empirical Relationship ◽  
Scale Model ◽  
Gas Bubble ◽  
Gas Flow Rate ◽  
Dimensionless Variable ◽  
Bubble Plumes ◽  
The Relationship

The need to rapidly mix treating agent into the oil of a ruptured ship tank motivated scale model experiments of mixing in square-bottomed tanks by gas bubble plumes, The mixing time is primarily governed by the gas flow rate, the plume length and the tank base dimensions; and is quite insensitive to tank height. An empirical relationship between the degree of mixing and a single dimensionless variable is developed and an explanation of the relationship in terms of the fundamentals of the flow is provided.

scholarly journals An Experimental and Simulated Study on Gas-Liquid Flow and Mixing Behavior in an ISASMELT Furnace

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 565 ◽  
Author(s):  
Hongliang Zhao ◽  
Tingting Lu ◽  
Pan Yin ◽  
Liangzhao Mu ◽  
Fengqin Liu
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Turbulent Viscosity ◽  
Mixing Time ◽  
Water Model ◽  
Mixing Efficiency ◽  
Gas Flow Rate ◽  
Factors Affecting ◽  
Sufficient Energy ◽  
Gas Liquid Flow

In this study, a water-model experiment and numerical simulation were carried out in a pilot ISASMELT furnace to study the factors affecting mixing time. The experimental results were compared to the simulation results to test the accuracy of the latter. To study the internal factors that affect the mixing time, the turbulent viscosity and flow field were calculated using simulation. In addition, following previous research, external factors that influence the mixing time including the depth of the submerged lance, lance diameter, gas flow rate, and the presence of a swirler were studied to investigate their effect on the flow regime. The results indicated that the mixing time is controlled by the turbulent viscosity and velocity vector. In addition, it was found that the lance diameter should not exceed 3.55 cm to maintain sufficient energy for stirring the bath. Finally, the optimal gas flow rate that offers the best mixing efficiency was found to be 50 Nm3/h.

Effect of Hole Distance and Hole Number on Bubble Behavior during Gas Injection with Multi-Hole Orifices

2011 ◽  
Vol 295-297 ◽  
pp. 1113-1119 ◽  
Author(s):  
Fang Jiang ◽  
Guo Guang Cheng
Keyword(s):  
Physical Model ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Injection ◽  
Critical Value ◽  
Refining Process ◽  
Hole Diameter ◽  
Gas Flow Rate ◽  
Bubble Behavior ◽  
Hole Number

Physical model experiments have been performed to clarify the effect of hole distance and hole number of multi-hole orifices on bubble behavior during metal refining process. It is found kA/V firstly decreases and then increases with the hole distance increasing. However, kA/V shows little further increase when hole distance exceeds a critical value. There exists an optimal hole distance for the multi-hole orifice, which is dependent on the gas flow rate, the hole diameter and the hole number in the multi-hole orifice. kA/V firstly increases with the hole number increasing, and then remains unchanged when hole number exceeds a critical value. There also exists an optimal hole number for the multi-hole orifice, which is closely related to the gas flow rate.

Sign in / Sign up

Export Citation Format

Share Document