Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process

In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler–Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).

Development of High-Performance Air Purifier using Human Hair and Vetiver (Chrysopogan Zizanioides) as Filter Media

Purpose-The global crisis of extreme air pollution is encountered nowadays due to the burning of fossil fuel, vehicular emission, modern sophistication and industrialization. These result infusions of high levels of Smoke, Particulate Matter (PM), Total volatile organic compounds (VOC), Hydrocarbons (HCHO), Nitrogen Oxides (NOX), Sulfur Oxides (SOX), Carbon Monoxide (CO) and other air pollutants into the atmosphere.Findings- Therefore, the development of a cost-saving air purifier is extremely essential with naturally occurring resources that are readily available throughout all the places at some point in time.A compact, flexible, modular and low-cost air purifier has designed employing a combination of porous plug and two filter media developed from natural resources.Methodology-The air purification unit is horizontal shaped and made with a simple PVC pipe. The first filter media was developed by mixing human hair with low-cost vegetable Mahua oil and the second one by wetting Vetiver (Chrysopogan zizanioides) with water. A mixture of human hair with Mahua oil can absorb the suspended particulate matter of size above 2.5 µm, and wet Vetiver shows the enormous capability of absorption of gases like NOx, SOx and Hydrocarbons and adsorption of particle size even less than 2.5 µm like PM1. Moreover, due to the pleasant smell, wet Vetiver can produce fresh air.Value-The cleaning and disposals of such naturally derived products are easy because of complete biodegradability and no negative impact on the environment. To restrict the filter media movement, porous plugs are coupled at the inlets and outlets of pipeline and filters. Due to the Joule-Thomson effect, the air coming out of the porous plug becomes 50oC cooler than the input air. The pollutant removal efficiency of indoor was found to be more than 60% were in the outdoor residential areas, it was more than 75%, and in the heavily crowded regions, it evaluated to be more than 65%. Amidst the alarming air pollution scenario throughout the world, such an invented device should be welcome due to the excellent performance as reflected in the production of pollutant-free fresh air at reduced temperature.

Influence of Gas Density and Plug Diameter on Plume Characteristics by Ladle Stirring

The paper presents new results concerning the influence of the gas density and porous plug diameter on the nature of liquid steel stirring with an inert gas in the ladle. The tests were carried out on a cold model of a 30t ladle using particle image velocimetry (PIV) with a high-speed camera to analyse the plume zone formed during the supply of argon and helium as a stirring gas. The similarity criteria for the investigation of stirring processes in cold model in the past were discussed and compared. The modified Morton number was used in this paper to relate the gas flow rate in the model with real objects. The presented results constitute complete documentation of the influence of the plug diameter and gas density on the size of formed gas bubbles and the velocity of gas bubbles rising in different zones of the plume, plume, and spout geometry, including the expansion angle, spout height, open eye area, and gas hold-up.

Numerical Modelling of the Influence of Argon Flow Rate and Slag Layer Height on Open-Eye Formation in a 150 Ton Steelmaking Ladle

A transient computational fluid dynamics (CFD) modelling approach was used to study the complex multi-phase flow in an argon-stirred industrial scale ladle with a nominal capacity of 150 tons. During the stirring process, when gas was injected through the porous plug from the bottom into the steel bath, it breaks up into bubbles and infringes the slag layer creating an open-eye. The volume of fluid model was used to investigate the open-eye formation process in the simulations. In the numerical simulations, the open-eye area changed from 0.7 to 2.24 m2 with the increment of argon flow rate from 200 to 500 NL/min for slag layer thickness of 40 cm. Furthermore, the influence of slag layer height on the open-eye area was investigated. An argon flow rate of 200 NL/min was able to break the slag layer for slag layer height of 40 cm, and the open-eye formation was not possible for the same flow rate when the slag layer height was elevated from 40 to 55 cm. The numerical simulation results were validated against industrial measurements carried out at Outokumpu Stainless located in Tornio, Finland. The numerical simulation results of dynamics and time-averages of the slag area showed a good agreement when compared to the industrial measurements. To conclude, it is necessary to define gas flow rate based on the slag layer height to have an open-eye suitable for alloying.

Mid-Infrared Polarization Spectroscopy Measurements of Species Concentrations and Temperature in a Low-Pressure Flame

We demonstrate quantitative measurements of methane (CH4) mole fractions in a low-pressure fuel-rich premixed dimethyl ether/oxygen/argon flat flame (Φ = 1.87, 37 mbar) using mid-infrared (IR) polarization spectroscopy (IRPS). Non-intrusive in situ detection of CH4, acetylene (C2H2), and ethane (C2H6) in the flame was realized by probing the fundamental asymmetric C–H stretching vibration bands in the respective molecules in the spectral range 2970–3340 cm−1. The flame was stabilized on a McKenna-type porous plug burner hosted in a low-pressure chamber. The temperature at different heights above the burner (HAB) was measured from the line ratio of temperature-sensitive H2O spectral lines recorded using IRPS. Quantitative measurements of CH4 mole fractions at different HAB in the flame were realized by a calibration measurement in a low-pressure gas flow of N2 with a small admixture of known amount of CH4. A comprehensive study of the collision effects on the IRPS signal was performed in order to quantify the flame measurement. The concentration and temperature measurements were found to agree reasonably well with simulations using Chemkin. These measurements prove the potential of IRPS as a sensitive, non-intrusive, in situ technique in low pressure flames.

Establishing the Optimum Composition of Superaluminous Refractory Products, Used for Steel Ladle Bubbling

It is widely acknowledged by all specialists in the field of ferrous metallurgy that the porous peg of the kit for injecting inert gases into the steel casting ladle is the weakness of the entire assembly. This is the most prompted piece due to the thermal shocks that occur when injecting cold gas and the wear and tear and corrosion caused by disturbances in the steel during the injection process. The porous structure of the peg considerably weakens the physical properties and widens the surface of metal - refractory material contact thus enabling the destructive chemical action. In addition, the process of injecting oxygen for cleaning the metal peg also contributes to the destructive action and the substantial decline in its endurance. All these considered, it has been decided that the material for producing these items should contain at least 95% Al2O3 which means using only tabular alumina. As far as the binder is concerned, it has been established that a liquid chemical binder made of colloidal alumina should be used since this does not considerably diminish the Al2O3 content of the end product. It is the aim of this paper to bring forward the author�s research regarding the production of the porous plug using high-alumina refractory materials.

Mechanisms performance and pressure dependence of hydrogen/air burner-stabilized flames

The kinetic mechanism of hydrogen combustion is the most investigated combustion system. This is due to extreme importance of the mechanism for combustion processes, i.e. it is present as a sub-mechanism in all mechanisms for hydrocarbon combustion systems. Therefore, detailed aspects of hydrogen flames are still under active investigations, e.g. under elevated pressure, under conditions of different heat losses intensities and local equivalence ratios etc. For this purpose, the burner stabilized flame configuration is an efficient tool to study different aspects of chemical kinetics by varying the stand-off distance, pressure, temperature of the burner and mixture compositions. In the present work, a flat porous plug burner flame configuration is revisited. A hydrogen/air combustion system is considered with detailed molecular transport including thermo-diffusion and with 8 different chemical reaction mechanisms. Detailed numerical investigations are performed to single out the role of chemical kinetics on the loss of stability and on the dynamics of the flame oscillations. As a main outcome, it was found/demonstrated that the results of critical values, e.g. critical mass flow rate, weighted frequency of oscillations and blow-off velocity, with increasing the pressure scatter almost randomly. Thus, these parameters can be considered as independent and can be used to improve and to validate the mechanisms of chemical kinetics for the unsteady dynamics.