| 1. |
- Tilliander, Anders, et al.
(författare)
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A mathematical model of the heat transfer and fluid flow in AOD nozzles and its use to study the conditions at the gas/steel interface
- 2001
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 41:10, s. 1156-1164
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of process gas parameters in the area where the gas leaves the nozzle and then enters the molten steel in AOD converters is necessary in order to determine the boundary conditions needed to model the converter process. Using a newly developed mathematical model for an AOD nozzle verified by comparison against laser Doppler anemometer measurements, the objective of this study was to predict characteristics of non-isothermal heat transfer and fluid flow at the nozzle for pure oxygen gas injected into an AOD converter. The inlet boundary conditions for the nozzle simulation were taken from plant data. The investigation showed that the thermodynamic and physical phenomena in the region where the gas enters the steel melt cannot be determined if the transformation of kinetic energy of gas into heat is not considered because this would amount to oversight of the influences of bubble frequency, temperature, etc. on the process. The possible ranges of bubble frequency and temperature for the nozzle conditions in the study were also determined.
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| 2. |
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| 3. |
- Andersson, Nils Å. I., et al.
(författare)
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An in-Depth Model-Based Analysis of Decarburization in the AOD Process
- 2012
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:11, s. 1039-1052
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Tidskriftsartikel (refereegranskat)abstract
- A previously reported flow and reaction model for an argon-oxygen decarburization converter was extended to also include a thermodynamic description. An in-depth study of the model results has been conducted to answer how concentrations of elements and species in the converter at different locations change with time. This may contribute to the understanding of the mechanisms of the refining procedure in the argon-oxygen decarburization process. The refining procedure includes several step-wise changes of an injected gas composition to higher and higher inert gas ratio, called step changes. A step change leads to a decreased partial pressure of carbon monoxide and maintains the decarburization at a higher efficiency. The results shows early and late concentration profiles for the first injection step and suggests a way to determine when a step change should be made. Moreover, the step change could be determined by calculating the carbon concentration profiles and deciding when the carbon concentration gradients start to diminish.
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| 5. |
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| 6. |
- Safavi Nick, Reza, et al.
(författare)
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A mathematical model of the solid flow behavior in a real dimension blast furnace : Effects of the solid volume fraction on the velocity profile
- 2013
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:10, s. 999-1010
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Tidskriftsartikel (refereegranskat)abstract
- A mathematical model based on the continuum mechanic concept has been developed to describe the profile of solid particles in a blast furnace with respect to the in-furnace conditions and characteristics, e.g., the shape and size of the deadman. The Navier-Stokes differential equation for multi-phase multi-dimensional space has been used to describe the behavior of existing phases. The equation has been modified to make it possible to describe the dual nature of the solid phase in the system by applying the concept of the solid surface stress to characterize the inter-granular surface interactions between particles. Since different phases co-exist in a blast furnace, the volume fraction plays an important role in a blast furnace. Therefore, the influence of three different packing densities (0.68, 0.71, and 0.74, respectively) on the profile of the flow in the upper part of a furnace down to the tuyeres level has been studied. It is shown that an increase in the volume fraction of the solid phase lead to a decrease in magnitude of the velocity. The decrease in the magnitude of the velocity due to an increase in the solid volume fraction will increase the resident time of the particles inside a blast furnace. In addition, it is shown that the solid phase velocity magnitude decreases from the throat to the belly of the furnace for the studied conditions. However, after belly the velocity magnitude increases.
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| 7. |
- Safavi Nick, Reza, et al.
(författare)
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Effect of Particle Properties on the Solid Flow Profile in a Blast Furnace
- 2009
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Ingår i: Journal of Iron and Steel Research International. - 1006-706X .- 2210-3988. ; 16:Part 2 Suppl. 2, s. 1112-1115
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Tidskriftsartikel (refereegranskat)abstract
- An ironmaking blast furnace is one of the most complex reactors working with a multiphase flow involving gas, liquid and solid. The solid phase is the most important phase among these three phases. Consequently, investigating the velocity profile of solid particles as a primary phase in the blast furnace is one of the major research focus during the last decay. Since the major outbreak of computer development during the last twenty years, mathematical modeling and numerical Solution plays an important role in the engineering development. Therefore, the solid particle behavior is modeled based on general conservation laws to investigate the profile of solid particles. The different properties of solid particles have different effect on the velocity profile of solid particles. Therefore, in this article, the effect of particle properties such as diameter, viscosity, density and volume fraction. on velocity profile of solid particles and blast furnace operation has been studied and reported.
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| 8. |
- Tilliander, Anders, et al.
(författare)
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A Three-Dimensional Three-Phase Model of Gas Injection in AOD Converters
- 2014
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:3, s. 376-387
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Tidskriftsartikel (refereegranskat)abstract
- A mathematical model of gas injection in the AOD converter process has been developed by augmentation of an earlier developed three-dimensional two-phase model to the slag phase and an industrial relevant geometry including six nozzles. The model is based on fundamental transport equations and includes separate solution of the steel and the gas phases and their coupling by friction as well as the slag phase. The 3D 3-phase (steel, slag, and gas) AOD model has been used to predict fluid flow, turbulence, and bubble characteristics as well as fluid-slag dispersion. In addition, two different gas flow rates have been simulated which resulted in quite different flow pattern. This new findings opens up for future investigations of gas-metal reactions in the AOD converter, which are of key interest from an industrial point of view.
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