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 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 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.

Effects of Slitting Size and Inlet Operating Conditions on Hydrogen Combustion Characteristics in a Micro-Combustor With a Controllable Vortex Slotted Bluff Body

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Yunfei Yan ◽  
Kaiming Shen ◽  
Yu Cui ◽  
Ziqiang He ◽  
Li Zhang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Bluff Body ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Flow Ratio ◽  
Gas Flow Rate ◽  
Slit Size ◽  
Micro Combustor

Abstract Effects of controllable vortex slotted bluff body parameters (position of a bluff body, slit size, and controllable flow ratio) on the combustion characteristics of hydrogen/air in a micro-combustor with a bluff body were investigated numerically. The results illustrated that the combustion efficiency of hydrogen decreases with increasing distance (L1) between the front edge of the bluff body and the combustor inlet. The combustion characteristics of the micro-combustor are optimum when L1 is 0 mm. The blow-off limit of the combustor reaches a maximum (564 cm3/s) when the slit width (d) is 20% of the bluff body width. The blow-off limit first increases and then decreases when the equivalence ratio (φ) increases and reaches a maximum (732 cm3/s) when φ is 1.0, and the controllable flow ratio is 0.2. The combustion efficiency of hydrogen is gradually increased with the increase in the controllable flow ratio. When φ is less than 1.0, the optimal controllable flow ratio gradually decreases with the increase in the premixed gas flow rate, and the optimal controllable flow ratio basically remains at 0.6 when the premixed gas flow rate is less than 360 cm3/s.

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.

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.

PIV Study of Flow in an Aerated Tank with a Hollow Blade Turbine

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Xuan Geng ◽  
Zhengming Gao ◽  
Yuyun Bao
Keyword(s):  
Liquid Phase ◽  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
Mean Velocity ◽  
Image Velocimetry

Liquid phase hydrodynamics in an aerated tank (ID = 0.19 m) stirred by a half elliptical blade disk turbine (HEDT) have been investigated using particle image velocimetry (PIV) under both aerated and unaerated conditions. The effect of the gas flow rate on the aerated mean velocity of the liquid phase, turbulent kinetic energy and turbulent kinetic energy dissipation are discussed, and their comparisons with those under unaerated conditions are also carried out. Under aerated conditions, the presence of gas does not remarkably change the velocity pattern of the liquid phase. When the direction of the liquid flow is the same as the buoyancy, the liquid is accelerated up to 10.4% by bubbles at position of z/T=0.8 and r/T=0.45; while the liquid flow reversely, the liquid is decelerated about 37.5% under the gas flow rate of 0.2 vvm at the position of z/T=0.25 and r/T=0.45. The turbulent kinetic energy in the bulk flow increases after introducing gas phase, and the average turbulent kinetic energy of the upper, middle and lower regions at 0.2 vvm are increased by 37.3%, 37.8% and 142.7%, respectively. Large-eddy PIV approach is carried out to estimate the distribution of the turbulence kinetic energy dissipation. The result shows that the distribution of the turbulent kinetic energy dissipation is similar as those of turbulent kinetic energy.

scholarly journals Effect of Nitrogen Flow Ratio on Degradation Behaviors and Failure of Magnetron Sputter Deposited Tantalum Nitride

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1133
Author(s):  
Zhigang Li ◽  
Yubao Zhang ◽  
Yi Wang ◽  
Jinfeng Li ◽  
Hongtao Zhao
Keyword(s):  
Sheet Resistance ◽  
Flow Rate ◽  
Gas Flow ◽  
Adhesion Force ◽  
Tantalum Nitride ◽  
Nitrogen Flow ◽  
Flow Ratio ◽  
Gas Flow Rate ◽  
Heating And Cooling ◽  
Degradation Behaviors

A series of Tantalum Nitride (TaN) films under a reactive direct current magnetron sputtering method with a controlled total gas flow rate were prepared on aluminum oxide substrates. To find the nitrogen flow rate, which produced the minimum sheet resistance, TaN films deposited under a nitrogen gas flow ratio of 2.5%, 5%, 10%, 15%, 20%, 25% were characterized in terms of their structural and electrical properties. The optimum total gas flow rate was 60 sccm, revealing the lowest deviation of sheet resistance. Next, the durability and reliability at high temperatures, after heating and cooling cycles and exposure to the induced current, were tested. When the nitrogen flow ratio reaches 2.5%, it gets the maximum for the adhesion force, roughness, and deposition rate of the TaN film, and maximum values are 75.4 N, 1.1 nm, and 3.67 nm/min, respectively, and the sheet resistance of the TaN film reaches a minimum of 20.32 Ω/sq. The degradation behaviors and failure of TaN films were investigated by measuring the sheet resistance variation. To further explain the degradation of TaN films, additional analysis of their crystallinity was conducted. The results showed that TaN-based thin film resistors have high durability and reliability, and are suitable for embedded passive resistors.

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