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  • 1.
    Alevanau, Aliaksandr
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Kantarelis, Efthymios
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Kuznechik, Olgerd
    Belarussian State University.
    Vyhoniailo, Oleksandr
    Mechanically assisted low temperature pyrolysis of hydrocarbons2014Inngår i: Proceedings of the XVII International Conference Foundations & Advances in Nonlinear Science, September 29 - October 3, Minsk 2014, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report experimental setups and conditions leading to pyrolysis (cracking) of such gaseous hydrocarbons as methane, mixed propane and butane, at the temper-atures of the heater below 200oC. The process was mechanically assisted by putting the substances being decomposed into a dynamic interaction with the tin and bismuth alloy. The alloy had periodically changing phase state thus creating fractal interfaces between its surface and the gases. Interaction of the gases with mechanically produced fractal surfaces of the alloy made possible gas decomposition even at lower temperatures of the heater (150oC). At this temperature the heater couldn't melt the alloy in the heated volume with the gas.

  • 2.
    Arzpeyma, Niloofar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Mathematical Modeling of Postcombustion in an Electric Arc Furnace (EAF)2019Inngår i: METALS, ISSN 2075-4701, Vol. 9, nr 5, artikkel-id 547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Numerical modeling was used to study the capability of postcombustion in an electric arc furnace (EAF) equipped with virtual lance burners. The CO flow rate at the molten bath surface was estimated using the off-gas data obtained close to the outlet of an EAF. Then, the effect of the secondary oxygen flow rate on postcombustion was studied. The results show a CO flow rate of 0.6 kgs(-1) and 0.8 kgs(-1) for operation modes of burner and burner + lancing. Increase of the secondary oxygen flow rates of 60% and 70% result in 17% and 7% increase in the postcombustion ratio (PCR) for the burner and burner lancing modes, respectively.

  • 3.
    Arzpeyma, Niloofar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Modeling of post combustion inside the off-gas duct system of the Ovako electric arc furnace2014Inngår i: CDF 2014: 10th International Conference on CFD in Oil & Gas, Metallurgical and Process Industries, SINTEF, Trondheim, Norway, 17-19 June 2014, Proceedings, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In order to study the post combustion (PC) inside the duct system of an electric arc furnace (EAF), a three-dimensional computational fluid-dynamics (CFD) model was developed. The reactions between the off gas species (oxygen and hydrogen) and oxygen which leaked into the duct, through the air gap, was considered. The off-gas composition, the off –gas velocity and the outlet pressure were considered as parameters affecting the PC. The results showed that there was a considerable amount of the uncombusted CO to be captured. The highest CO concentration was found at the central part of the duct. The results also showed that a higher off-gas mass flow rate and a higher power of the outlet fan led to a higher combustion of CO and H2. An off-gas analysis probe was then installed after the air gap, where the tip of the probe was placed according to the predicted high CO concentration area found in the simulations. Thereafter, the measured off-gas composition was used to predict the off-gas composition at the outlet of the EAF.

  • 4.
    Arzpeyma, Niloofar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Widlund, Ola
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Mathematical Modeling of Scrap Melting in an EAF Using Electromagnetic Stirring2013Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, nr 1, s. 48-55Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Numerical modeling has been used to investigate the influence of electromagnetic stirring on melting of a single piece of scrap in an eccentric bottom tapping (EBT) electric arc furnace (EAF). The heat transfer and fluid flow in the melt for both conditions with and without electromagnetic stirring were studied. The buoyancy and electromagnetic forces were considered as the source terms for momentum transfer in the studied conditions. The enthalpy-porosity technique was applied to track the phase change of a scrap piece defined in the EBT region of the furnace. Different scrap sizes, preheating temperatures, stirring directions and force magnitudes were considered, and the heat transfer coefficient was estimated from the heat transfer rate at the melt-scrap interface. The results showed that electromagnetic stirring led to a reduced melting time and an increased heat transfer coefficient by a factor of four. The results for Nusselt number versus Grashof number for natural convection and Reynolds number for electromagnetic stirring were compared with those obtained through correlations from previous studies.

  • 5.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Par
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Effect of TurboSwirl Structure on an Uphill Teeming Ingot Casting Process2015Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, nr 6, s. 2652-2665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To produce high-quality ingot cast steel with a better surface quality, it would be beneficial for the uphill teeming process if a much more stable flow pattern could be achieved in the runners. Several techniques have been utilized in the industry to try to obtain a stable flow of liquid steel, such as a swirling flow. Some research has indicated that a swirl blade inserted in the horizontal and vertical runners, or some other additional devices and physics could generate a swirling flow in order to give a lower hump height, avoid mold flux entrapment, and improve the quality of the ingot products, and a new swirling flow generation component, TurboSwirl, was introduced to improve the flow pattern. It has recently been demonstrated that the TurboSwirl method can effectively reduce the risk of mold flux entrapment, lower the maximum wall shear stress, and decrease velocity fluctuations. The TurboSwirl is built at the elbow of the runners as a connection between the horizontal and vertical runners. It is located near the mold and it generates a tangential flow that can be used with a divergent nozzle in order to decrease the axial velocity of the vertical flow into the mold. This stabilizes flow before the fluid enters the mold. However, high wall shear stresses develop at the walls due to the fierce rotation in the TurboSwirl. In order to achieve a calmer flow and to protect the refractory wall, some structural improvements have been made. It was found that by changing the flaring angle of the divergent nozzle, it was possible to lower the axial velocity and wall shear stress. Moreover, when the vertical runner and the divergent nozzle were not placed at the center of the TurboSwirl, quite different flow patterns could be obtained to meet to different requirements. In addition, the swirl numbers of all the cases mentioned above were calculated to ensure that the swirling flow was strong enough to generate a swirling flow of the liquid steel in the TurboSwirl.

  • 6.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Numerical study of an application of a divergent reverse TurboSwirl nozzle in the billet continuous casting process2019Inngår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 46, nr 2, s. 148-158Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The swirling flow has widely been investigated for liquid steel flowing in the continuous casting process. In this paper, a new design of the submerged entry nozzle (SEN) is applied by using a reverse TurboSwirl device with a divergent nozzle. This divergent reverse TurboSwirl nozzle (DRTSN) is shown to gain a more beneficial flow pattern compared to the straight nozzle. A stronger swirling flow can be obtained at the SEN outlet, which leads to a calmer flow field and an appropriately active meniscus flow that could improve the heat and mass transfer near the meniscus. The swirl number in the SEN is independent of the casting speed, while a lower casting speed yields a lower maximum wall shear stress. The DRTSN is connected to the tundish by an elbow and a horizontal runner. A longer horizontal runner supplies a more uniform velocity profile and a more symmetrical flow pattern.

  • 7.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    The physical and mathematical modelling of swirling flow by turboswirl in an uphill teeming ingot casting process2015Inngår i: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, s. 473-476Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Ingot casting is widely used to produce some certain specialty steel grades. During the process of teeming the liquid steel from the ladle to the mould for a final solidification, the high velocity of the liquid steel can result in an uneven flow pattern either in the vertical and horizontal runners or in the mould. This can cause some serious problems, such as a high erosion of refractory walls or a mould flux entrapment. Here, some research indicate that a swirling flow is beneficial for making the flow pattern even and for reducing turbulence in the runners. Recently, a new swirling flow generation component, TurboSwirl, was applied to improve the flow pattern of the liquid steel as it flows into the mould so that a more stable flow could be obtained. The TurboSwirl is located on the intersection of the horizontal and vertical runners near the mould. It generates a tangential flow that can be used with an expanding nozzle with a flaring angle in order to decrease the vertical flow velocity. Moreover, a mathematical model has been developed to optimize the geometry of the physical model. The results shows that a much more beneficial flow pattern can be obtained by reducing the flaring angle or moving the vertical runner to an off-center position of the TurboSwirl, according to the numerical models. Therefore, a water modelling experiment was built, including the TurboSwirl, one mould and the runners. Tracers will be mixed into the water to detect the flow pattern and the velocity of the fluid would be recorded by a digital motion analysis recorder for later analysis. Firstly, different flaring angles of the expanding nozzle were simulated and compared. The results could supply a good support to the following water modelling experiments and to prove that the TurboSwirl setup produces a much calmer initial filling of the mould, compared to a conventional setup.

  • 8.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    An Experimental and Numerical Study of Swirling Flow Generated by TurboSwirl in an Uphill Teeming Ingot Casting Process2016Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 56, nr 8, s. 1404-1412Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A swirling flow has been demonstrated to be beneficial for making the flow pattern even and to reduce turbulence during filling in ingot casting. A new swirling flow generation device, TurboSwirl, was applied to improve the flow pattern of the liquid steel as it flows into the mold so that a more stable flow could be obtained. A water model was built including the TurboSwirl with different flaring angles of the divergent nozzle, according to a former numerical study indicating that a much more beneficial flow pattern could be obtained by reducing the flaring angle. To validate the mathematical model, the air-core vortex formed in the water model experiment was used, and the length of the vortex was measured and compared to the numerical predictions. Different turbulence models including the standard k-epsilon, realizable k-epsilon and Reynolds stress model were tested. It was found that only the Reynolds stress model could most accurately simulate the high swirling flow including a vortex. In addition, the radial velocity of the water around the vortex was measured by an ultrasonic velocity profiler (UVP). The experimental results revealed a high turbulence of the swirling flow and strong fluctuations of the vortex. The radial velocity of the water around the upper part of the vortex could be predicted well compared to the experimental results by the UVP measurements.

  • 9.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Experimental Validation and Numerical Analysis of the Swirling Flow in a Submerged Entry Nozzle and Mold by using a Reverse TurboSwirl in a Billet Continuous Casting Process2016Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As an alternative to some traditional methods to generate a swirling flow in the continuous casting process, the use of a new swirling flow generator, TurboSwirl, was studied. Specifically, a reversed TurboSwirl device was designed as part of a submerged entry nozzle (SEN) for a round billet continuous casting process. Mathematical modelling was used to investigate this new design and a water model experiment was carried out to validate the mathematical model. The predicted velocities by the turbulence models: realizable k-ε model, Reynold stress model (RSM) and detached eddy simulation (DES) were compared to the measured results from an ultrasound velocity profile (UVP) method. The DES model could give the best prediction inside the SEN and had a deviation less than 3.1% compared to the measured results. Moreover, based on the validated mathematical model and the new design of the SEN, the effect of the swirling flow generated by the reverse TurboSwirl on the flow field of the SEN and mold was compared to the design of the electromagnetic swirl flow generator (EMSFG). A very strong swirling flow in the SEN and a stable flow pattern in the mold could be obtained by the reverse TurboSwirl compared to the EMSFG. 

  • 10.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Numerical Study of the Application for the Divergent Reverse TurboSwirl Nozzle in the Billet Continuous Casting ProcessManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The swirling flow is demanded from the submerged entry nozzle (SEN) to the mold for the continuous casting process. A new design of the SEN is applied by using the reverse TurboSwirl. The TurboSwirl has been proved that it can provide a more stable flow pattern of the liquid steel in the mold. It also can supply a strong enough swirling flow compared to other swirling flow generation methods. Furthermore, a divergent nozzle is added to replace the bottom part of the straight SEN. This new divergent reverse TurboSwirl nozzle (DRTSN) could gain a more beneficial flow pattern in the mold compared to the straight nozzle. The numerical results reveals that a stronger swirling flow can be gained at the SEN outlet with a calmer flow field and active meniscus flow. It is also found that the swirl intensity in the SEN is independent of the casting speed. Lower casting speed is more desired due to a lower maximum wall shear stress. The DRTSN is connected to the tundish by an elbow and a horizontal runner. Longer horizontal runner can supply a more uniform velocity profile and symmetrical flow pattern in the mold. 

  • 11.
    Bai, Haitong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ni, Peiyuan
    Northeastern Univ, Sch Met, Key Lab Ecol Met Multimet Intergrown Ores, Educ Minist, Shenyang 110819, Liaoning, Peoples R China.;Osaka Univ, Grad Sch Engn, Dept Mat & Mfg Sci, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan..
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhang, Tingan
    Northeastern Univ, Sch Met, Key Lab Ecol Met Multimet Intergrown Ores, Educ Minist, Shenyang 110819, Liaoning, Peoples R China..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Effect of swirling flow tundish submerged entry nozzle outlet design on multiphase flow and heat transfer in mould2019Inngår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effect of a swirling flow SEN (submerged entry nozzle) outlet design on the multiphase flow and heat transfer in a mould was investigated by using numerical simulation. It was found that different SEN outlet designs could form different flow patterns and temperature distributions on the upper of the mould. The enlarged outlet SEN design had an effect to decrease the horizontal velocity of liquid steel flowing out the SEN outlet, reducing the steel flow velocity towards the solidification front. Although a higher velocity was found near the slag/steel interface with the enlarged outlet SEN, but the turbulent kinetic energy was lower. The reason was that less circulation flows were formed in the region of the mould top. The weak horizontal flow towards the solidification front with the enlarged outlet SEN induced lower wall shear stresses, at the same time it also formed a lower temperature distribution near the solidified shell.

  • 12.
    Bölke, Kristofer
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Andersson, Nils A. I.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Imris, Matej
    ScanArc Plasma Technol AB, SE-81321 Hofors, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Experimental Determinations of Mixing Times in the IronArc Pilot Plant Process2019Inngår i: METALS, ISSN 2075-4701, Vol. 9, nr 1, artikkel-id 101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    IronArc is a newly developed technology and an emerging future process for pig iron production. The long-term goal with this technology is to reduce the CO2 emissions and energy consumption compared to existing technologies. The production rate of this process is dependent on the stirring, which was investigated in the pilot plant process by measuring the mixing time in the slag bath. Moreover, slag investigations were done both based on light optical microscope studies as well as by Thermo-Calc calculations in order to determine the phases of the slag during operation. This was done because the viscosity (which is another important parameter) is dependent on the liquid and solid fractions of the slag. The overall results show that it was possible to determine the mixing time by means of the addition of a tracer (MnO2 powder) to the slag. The mixing time for the trials showed that the slag was homogenized after seconds. For two of the trials, homogenization had already been reached in the second sample after tracer addition, which means <= 8 s. The phase analysis from the slag indicated that the slag is in a liquid state during the operation of the process.

  • 13.
    Bölke, Kristofer
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Imris, Matej
    ScanArc Plasma Technol AB, SE-81321 Hofors, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Importance of the Penetration Depth and Mixing in the IRONARC Process2018Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 58, nr 7, s. 1210-1217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the most important parameters for gas injection into liquid baths is the penetration depth of the gas into the bath. This is due to that it strongly influences the flow structure and hence the stirring and plume behavior in metallurgical processes. The IRONARC process is a new energy efficient process for reduction of iron oxide to produce pig iron. The future goal is to continuously scale up the process to an industrial scale from the current pilot scale. In this process, gas is injected horizontally through a submerged nozzle into a slag bath. Hence, the penetration depth is of great importance since it greatly affect several parameters in this process. Moreover, this information is essential when scaling up the reactor from a pilot scale to an industrial scale. In this work, the penetration depth of gas injection into water in a small scale side blown converter was studied numerically. Two different approaches with different multiphase models were tested, namely the Volume of Fluid (VOF) model and Eulerian multiphase model (EE). The penetration depth could be accurately determined for both numerical models, with a small expected deviation of 13.9% from the physical experiment results. Also, the simulation time was shorter for the Eulerian multiphase model. The penetration depth was then determined for the IRONARC pilot plant process. The results show that the plume is detached from the nozzle wall, which in turn results in a better energy usage of the gas along with a small refractory wear.

  • 14.
    Bölke, Kristofer
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ni, Peiyuan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Swartling, Maria
    ScanArc Plasma Technol AB, SE-81321 Hofors, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Physical Modeling Study on the Mixing in the New IronArc Process2018Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, nr 7, artikkel-id 1700555Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    IronArc is a newly developed technology for pig iron production with the aim to reduce the CO2 emission and energy consumption, compared to a conventional blast furnace route. In order to understand the fluid flow and stirring in the IronArc reactor, water modeling experiments are performed. Specifically, a down scaled acrylic plastic model of the IronArc pilot plant reactor is used to investigate the mixing phenomena and gas penetration depth in the liquid bath. The mixing time is determined by measuring the conductivity in the bath, after a sodium chloride solution is added. Moreover, the penetration depth is determined by analyzing the pictures obtained during the experimental process by using both a video camera and a high speed camera. The results show that the bath movements are strong and that a circular movement of the surface is present. The mixing in the model for the flow rate of 282 NLmin(-1) is fast. Specifically, the average mixing times are 7.6 and 10.2s for a 95% and a 99% homogenization degree, respectively. This is 15% and 18% (per degree of homogenization) faster compared to the case when using 3 gas inlets and the same flow rate.

  • 15.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Colocated pressure-velocity coupling in finite difference methods2019Inngår i: Progress in Computational Fluid Dynamics, An International Journal, ISSN 1468-4349, E-ISSN 1741-5233, Vol. 19, nr 5, s. 273-281Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple method to be used for colocated pressure-velocity coupling in incompressible flows is presented with a full derivation. A number of standard test cases are shown that demonstrate the ability of the method to produce accurate results. The method avoids spurious pressure oscillations while keeping the pressure Poisson equation stencil compact. This is obtained by discretising the continuity and pressure derivatives with first order differences with opposite directions, i.e., backward difference for continuity and forward difference for pressure (BCFP). The equations are also approximated using a forward difference for continuity and a backward difference for pressure (FCBP). In order to obtain a second order approximation the mean between BCFP and FCBP is used, i.e., a central difference. The paper gives a useful alternative to existing methods for pressure-velocity coupling in finite difference methods in which a staggered arrangement is not desirable.

  • 16.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Fundamental Experimental and Numerical Investigation Focusing on the Initial Stage of a Top-Blown Converter Process2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis work is to increase the knowledge of phenomena taking place during the initial stage in a top blown converter. The work has been done in a few steps resulting in four different supplements. Water model experiments have been carried out using particle image velocimetry (PIV) technology. The system investigated was a fundamental top blown converter where an air jet was set to impinge on a water surface. The flow field of the combined blown case, where an air jet was introduced through a bottom nozzle, was also captured by the PIV. The work clearly showed that the flow field caused by an impinging top blown jet alone could not match that of the bottom blown case. The main re-circulation loop (or vortex) was investigated with respect to position and it was found that an increased flow rate pushes the center of the re-circulation loop downwards into the bath. However, for the top-blown case there is a point when the flow rate is too large to cause a distinguishable re-circulation loop since the jet becomes more plunging (i.e. penetrates deep into the bath) than impinging, with large surface agitation and splashing as a result.A numerical model with the same dimensions as the experimental system was then created. Three different turbulence models from the same family were tested: standard-, realizable- and a modified-(slight modification of one of the coefficients in order to produce less spreading of the air jet) k-ε turbulence model. It could be shown that for the family of k-ε turbulence models the difference in penetration depth was small and that the values corresponded well to literature data. However, when it comes to the position of the re-circulation loop it was shown that the realizable k-ε model produced better results when comparing the results to the experimental data produced from the PIV measurements, mentioned earlier.It was then shown how the computational fluid dynamics (CFD) model could be coupled to thermodynamics databases in order to solve for both reactions and transport in the system. Instead of an air-water system, a gas-steel-slag system was created using the knowledge obtained in the previous simulation step described above. Reactions between gas-steel, gas-slag, steel-slag and gas-steel-slag were considered. Extrapolation of data from a few seconds of simulation was used for comparison to experimental data from the literature and showed reasonable agreement. The overall conclusion was that it is possible to make a coupling of the Thermo-Calc databases and a CFD software to make dynamic simulations of metallurgical processes such as a top-blown converter.A parametric study was then undertaken where two different steel grades were tested; one with high initial carbon content (3.85 mass-%) and one with lower carbon content (0.5 mass-%). The initial silicon content was held constant at 0.84 mass-%. Different initial temperatures were tested and also some variation in initial dissolved oxygen content was tried. It was found that the rate of decarburization/desiliconization was influenced by the temperature and carbon concentration in the melt, where a high temperature as well as a high carbon concentration favors decarburization over desiliconization. It was also seen that the region affected by a lower concentration of alloys (or impurities) was quite small close to the axis where the impinging jet hits the bath. Add the oscillating nature of the cavity and it was realized that sampling from this region during an experiment might be quite difficult.

  • 17.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Dynamic Coupling of Computational Fluid Dynamics and Thermodynamics Software: Applied on a Top Blown Converter2008Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, nr 2, s. 147-153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel modeling approach is presented where a computational fluid dynamics software is coupled to thermodynamic databases to obtain dynamic simulations of metallurgical process phenomena. The modeling approach has been used on a fundamental model of a top-blown converter. Reactions between gas-steel, gas-slag, steel-slag and gas-steel-slag have been considered. The results show that the mass transport in the surface area is totally controlled by convection. Also, that a large amount of CO produced during the decarburization might slow down the rate of decarburization in droplets ejected from the bath. For the present simulation conditions reflecting laboratory experiments, it was also seen that the amount of slag (FeO and/or SiO2) created is close to zero, i.e. only gas (CO+CO2) is created as the oxygen jet hits the steel bath. It was also illustrated how an extrapolation of the decarburization rate, sampled from a few seconds of simulation, could be done to get a rough estimate of the carbon content at a later stage in the process as long as the carbon content is relatively high. The overall conclusion is that it is possible to make a dynamic coupling of the Thermo-Calc databases and a CFD software to make dynamic simulations of metallurgical processes such as a top-blown converter.

  • 18.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Dynamic Modeling of Steel, Slag and Gas Reactions during Initial Blowing in a Top-Blown Converter2008Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A dynamic modeling approach is presented where a computational fluid dynamics software is coupled to a thermodynamics software to obtain simulations of reactions between steel, slag and gas in a top-blown converter. For each simulation the transport of momentum, energy and mass of species as well as the thermodynamic equilibrium in each cell containing at least two phases was treated. The overall conclusion is that the present calculation procedure is successful for dynamic simulations of interaction between an oxygen gas jet with a melt and a slag. The predicted rate of decarburization was found to agree well with experimental data from laboratory trials. In addition, four cases where simulated for which the temperature, the dissolved carbon content and the dissolved oxygen content were varied. The most important findings from these comparisons were that: i) a higher initial oxygen concentration in the melt yields a larger decarburization rate, ii) carbon content also plays a big role for the desiliconization where a low carbon content is required for desiliconization to take place, iii) decarburization and desiliconization is largely influenced by the temperature at which reactions take place, where low temperature favors desiliconization and iv) the region affected by a lower carbon/silicon concentration (hot-spot region) directly below the jet was approximately 10 mm for the current setup.

  • 19.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Termodynamisk modellering.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Dynamic modelling of steel, slag and gas during initial blowing in a top-blown converter2011Inngår i: Steel Grips - Journal of Steel and Related Materials, ISSN 1611-4442, E-ISSN 1866-8453, nr 9, s. 41-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A coupling between computational fluid dynamics (CFD) and thermodynamics has recently been done. In the current model improvement, a more realistic model was developed, where the numbers of gas species and slag phases were increased. For each simulation the transport of momentum, energy and mass of species as well as the thermodynamic equilibrium in each cell containing at least two phases was treated. Read how this calculation procedure can handle dynamic simulations of interaction between an oxygen gas jet, a melt and a slag. How is the agreement between the predicted rate of decarburization and experimental data? Which findings were achieved from the simulation of four cases varying the temperature, the dissolved carbon content and the dissolved oxygen content?

  • 20.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Review on CFD Simulation and Modeling of Decarburization Processes2018Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, nr 1, artikkel-id UNSP 1700108Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Over the last few decades, a number of CFD models have been dedicated to increasing the understanding of the decarburization processes in steelmaking. However, these processes are highly complex with large variations in time and length, and this makes the systems extremely demanding to simulate. Several reports have been published where parts of the processes have been investigated numerically, but to date no models have been presented that can handle the entire complexity of the processes. Here, a review of the research performed on the subject from 1998 to 2016 is given. A table summarizing the models used and the key focus of the studies is given, and it can be concluded that the effort put in so far to investigate the decarburization in steelmaking is substantial, but not complete. The currently available numerical models give an insight into process parameters such as reactions, mixing time, temperature distribution and thermal losses, off-gas post combustion and de-dusting, and also nozzle configuration. With the recent developments in numerical modeling and the increase in hardware capability, the future of simulation and modeling of the decarburization processes in steelmaking seems bright.

  • 21.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Iguchi, Manabu
    Hokkaido Univ, Grad Sch Engn, Div Mat Sci & Engn.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Fluid Flow in a Combined Top and Bottom Blown Reactor2006Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 46, nr 8, s. 1137-1142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Physical modeling was done to study the flow field in a cylindrical bath agitated by bottom purging, top lance blowing and a combination of both injection types. A particle image velocimetry (PIV) system has been used to capture the velocity field of all three cases mentioned above. Special attention was paid to the recirculation loop. Top blowing creates a re-circulation loop in a relatively small volume close to the surface, compared to bottom- and combined-blowing. Increasing bottom flow rate moves the center of the re-circulation loop downwards into the liquid. When top blowing is combined with bottom blowing the center of the re-circulation loop is moved downwards into the liquid with increasing top lance flow rate.

  • 22.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    A Mathematical Model of an Impinging Air Jet on a Water Surface2008Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, nr 4, s. 377-384Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A fundamental mathematical model of the flow field and surface deformation caused by an impinging jet in a top blown reactor has been developed. The results have been validated against water model experiments. More specifically, the predicted penetration depth has been found to agree well with surface deformation measurements and predictions using analytical equations. Furthermore, the predictions of the location of a vortex have been found to agree fairly well with PIV measurements. Calculations were also done to compare the widely used standard k-ε model against the realizable extension of the standard k-ε model to calculate the turbulent conditions of the flow. It was found that the penetration depth caused by the impinging jet on the liquid surface is relatively unaffected by the choice of turbulence model employed. However, when the main re-circulation loop in the bath was investigated there was a clear distinction in the flow fields produced when the two different turbulence models were used.

  • 23.
    Ersson, Mikael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Coupled thermodynamic and kinetic modeling of a top-blown bath2006Inngår i: Sohn International Symposium Advanced Processing of Metals and Materials, Vol 2: Thermo And Physicochemical Principles: Iron And Steel Making / [ed] Kongoli, F; Reddy, RG, 2006, s. 271-281Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A fundamental mathematical model of lance blowing on a bath surface has been developed with a purpose to increase the understanding of various phenomena in top blown oxygen converters. The model is based on the Navier-Stokes equations and turbulence is predicted using the k-epsilon model. In the present model the deformation of the liquid surface, caused by the impinging gas jet, is described using a VOF formulation. The mathematical model results have been verified by comparing predicted penetration-depth data with experimental results from physical model trials. The fluid dynamic modeling has also been coupled with the thermodynamic modeling to predict the reaction rate/distribution occurring in the vessel. The focus has been on carbon and a qualitative comparison of the predicted carbon content in the hot spot area and in droplets with experimental data from laboratory trials has been done.

  • 24.
    Khodabandeh, Erfan
    et al.
    Amirkabir Univ Technol, Tehran Polytech, Mech Engn Dept, 424 Hafez Ave,POB 15875-4413, Tehran, Iran..
    Akbari, Omid Ali
    Islamic Azad Univ, Young Researchers & Elite Club, Khomeinishahr Branch, Khomeinishahr, Iran..
    Toghraie, Davood
    Islamic Azad Univ, Dept Mech Engn, Khomeinishahr Branch, Khomeinishahr 84175119, Iran..
    Saffari Pour, Mohsen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap. Sharif Univ Technol, Dept Mech Engn, Tehran, Iran..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Numerical investigation of thermal performance augmentation of nanofluid flow in microchannel heat sinks by using of novel nozzle structure: sinusoidal cavities and rectangular ribs2019Inngår i: Journal of the Brazilian Society of Mechanical Sciences and Engineering, ISSN 1678-5878, E-ISSN 1806-3691, Vol. 41, nr 10, artikkel-id UNSP 443Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we present a numerical simulation of a laminar, steady and Newtonian flow of f-graphene nanoplatelet/water nanofluid in a new microchannel design with factors for increasing heat transfer such as presence of ribs, curves to enable satisfactory fluid mixing and changing fluid course at the inlet and exit sections. The results of this study show that Nusselt number is dependent on nanoparticles concentration, inlet geometry and Reynolds number. As the nanofluid concentration increases from 0 to 0.1% and Reynolds number from 50 to 1000, the Nusselt number enhances nearly up to 3% for increase in fluid concentration and averagely from 15.45 to 54.1 and from 14.5 to 55.9 for geometry with and without rectangular rib, respectively. The presence of ribs in the middle section of microchannel and curves close to hot walls causes a complete mixing of the fluid in different zones. When the nanoparticles concentration is increased, the pressure drop and velocity gradient will become higher. An increased concentration of nanoparticles in contribution with higher Reynolds numbers only increases the fraction factor slightly. (The fraction factor increases nearly 37% and 35% for Re = 50 and 1000, respectively.) The highest uniform temperature distribution can be found in the first zones of fluid in the microchannel and by further movement of fluid toward exit section, because of decreasing difference between surface and fluid temperature, the growth of temperature boundary layer increases and results in non-uniformity in temperature distribution in microchannel and cooling fluid. With decrease in the concentration from 0 to 0.1%, the average outlet temperature and FOM decrease nearby 0.62% and 6.15, respectively.

  • 25.
    Liu, Yu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Bai, Haitong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Liu, Heping
    Cent Iron & Steel Res Inst, 76 Xueyuan Nanlu, Beijing 100081, Peoples R China..
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Gan, Yong
    Cent Iron & Steel Res Inst, 76 Xueyuan Nanlu, Beijing 100081, Peoples R China..
    Physical and Numerical Modelling on the Mixing Condition in a 50 t Ladle2019Inngår i: METALS, ISSN 2075-4701, Vol. 9, nr 11, artikkel-id 1136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bubbly flow and mixing conditions for gas stirring in a 50t ladle were investigated by using physical modelling and mathematical modelling. In the physical modelling, the effect of the porous plugs' configurations on the tracer homogenization was studied by using a saturated NaCl solution to predict the mixing time and a color dye to show the mixing pattern. In the mathematical modelling, the Euler-Lagrange model and species transport model were used to predict the flow pattern and tracer homogenization, respectively. The results show that, for a +/- 5% homogenization degree, the mixing time with dual plugs using a radial angle of 180 degrees is shortest. In addition, the mixing time using a radial angle of 135 degrees decreases the most with an increased flow rate. The flow pattern and mixing conditions predicted by mathematical modelling agree well with the result of the physical modelling. For a +/- 1% homogenization degree, the influence of the tracer's natural convection on its homogenization pattern cannot be neglected. This is especially true for a 'soft bubbling' case using a low gas flow rate. Overall, it is recommended that large radial angles in the range of 135 degrees 180 degrees are chosen for gas stirring in the present study when using dual porous plugs.

  • 26.
    Liu, Yu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Liu, H.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Gan, Y.
    Comparison of Euler-Euler Approach and Euler–Lagrange Approach to Model Gas Injection in a Ladle2019Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 90, nr 5, artikkel-id 1800494Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The gas injection in a ladle using a porous plug is simulated using both the Euler-Euler and Euler-Lagrange approaches. The effects of various forces, bubble sizes, and bubble injection frequencies on the flow pattern are modeled. For predicting axial velocity and turbulent kinetic energy, the Euler-Lagrange approach fits better than Euler-Euler approach with the measured data. In the Euler-Euler approach, differences in axial velocities and turbulent kinetic energies for various bubble sizes mainly appears in the plume zone. In the Euler-Lagrange approach, different bubble sizes with the same injection frequency have a small impact on the turbulence dissipation. Furthermore, the turbulent dispersion from the gas phase to the liquid phase has an important effect on the plume structure and spout eye formation. For both modeling, the smaller the bubble diameter is, the larger the axial velocity and turbulent kinetic dissipation are in the central zone. For the bubble coalescence and breakup, according to the comparison of two modeling approaches, the Euler-Lagrange approach is more accurate in predicting the flow pattern for gas injection with a porous plug in the ladle.

  • 27.
    Liu, Yu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi. Central Iron and Steel Research Institute, Beijing, P.R. China.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Liu, Heping
    Cent Iron & Steel Res Inst, Beijing 100081, Peoples R China..
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Gan, Yong
    Cent Iron & Steel Res Inst, Beijing 100081, Peoples R China..
    A Review of Physical and Numerical Approaches for the Study of Gas Stirring in Ladle Metallurgy2019Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, nr 1, s. 555-577Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This article presents a review of the research into gas stirring in ladle metallurgy carried out over the past few decades. Herein, the physical modeling experiments are divided into four major areas: (1) mixing and homogenization in the ladle; (2) gas bubble formation, transformation, and interactions in the plume zone; (3) inclusion behavior at the steel-slag interface and in the molten steel; and (4) open eye formation. Several industrial trials have also been carried out to optimize gas stirring and open eye formation. Approaches for selecting criteria for scaling to guarantee flow similarity between industrial trials and physical modeling experiments are discussed. To describe the bubble behavior and two-phase plume structure, four main mathematical models have been used in different research fields: (1) the quasi-single-phase model, (2) the volume of fluid (VOF) model, (3) the Eulerian multiphase (E-E) model, and (4) the Eulerian-Lagrangian (E-L) model. In recent years, the E-E model has been used to predict gas stirring conditions in the ladle, and specific models in commercial packages, as well as research codes, have been developed gradually to describe the complex physical and chemical phenomena. Furthermore, the coupling of turbulence models with multiphase models is also discussed. For physical modeling, some general empirical rules have not been analyzed sufficiently. Based on a comparison with the available experimental results, it is found that the mathematical models focusing on the mass transfer phenomenon and inclusion behaviors at the steel-slag interface, vacuum degassing at the gas-liquid interface, dissolution rate of the solid alloy at the liquid-solid interface, and the combination of fluid dynamics and thermodynamics need to be improved further. To describe industrial conditions using mathematical methods and improve numerical modeling, the results of physical modeling experiments and industrial trials must offer satisfactory validations for the improvement of numerical modeling.

  • 28. Ni, P.
    et al.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processteknologi.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhang, T. -A
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Effect of immersion depth of a swirling flow tundish SEN on multiphase flow and heat transfer in Mold2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 11, artikkel-id 910Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of the immersion depth of a new swirling flow tundish SEN (Submerged Entry Nozzle) on the multiphase flow and heat transfer in a mold was studied using numerical simulation. The RSM (Reynolds Stress Model) and the VOF (Volume of Fluid) model were used to solve the steel and slag flow phenomena. The results show that the SEN immersion depth can significantly influence the steel flow near the meniscus. Specifically, an increase of the SEN immersion depth decreases the interfacial velocity, and this reduces the risk for the slag entrainment. The calculated Weber Number decreases from 0.8 to 0.2 when the SEN immersion depth increases from 15 cm to 25 cm. With a large SEN immersion depth, the steel flow velocity near the solidification front, which is below the mold level of SEN outlet, was increased. The temperature distribution has a similar distribution characteristic for different SEN immersion depths. The high temperature region is located near the solidification front. Temperature near the meniscus was slightly decreased when the SEN immersion depth was increased, due to an increased steel moving distance from the SEN outlet to the meniscus.

  • 29.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    A study on the nonmetallic inclusion motions in a swirling flow submerged entry nozzle in a new cylindrical tundish design2018Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 49, nr 2, s. 723-736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different sizes and shapes of nonmetallic inclusions in a swirling flow submerged entry nozzle (SEN) placed in a new tundish design were investigated by using a Lagrangian particle tracking scheme. The results show that inclusions in the current cylindrical tundish have difficulties remaining in the top tundish region, since a strong rotational steel flow exists in this region. This high rotational flow of 0.7 m/s provides the required momentum for the formation of a strong swirling flow inside the SEN. The results show that inclusions larger than 40 µm were found to deposit to a smaller extent on the SEN wall compared to smaller inclusions. The reason is that these large inclusions have Separation number values larger than 1. Thus, the swirling flow causes these large size inclusions to move toward the SEN center. For the nonspherical inclusions, large size inclusions were found to be deposited on the SEN wall to a larger extent, compared to spherical inclusions. More specifically, the difference of the deposited inclusion number is around 27 pct. Overall, it was found that the swirling flow contains three regions, namely, the isotropic core region, the anisotropic turbulence region and the near-wall region. Therefore, anisotropic turbulent fluctuations should be taken into account when the inclusion motion was tracked in this complex flow. In addition, many inclusions were found to deposit at the SEN inlet region. The plotted velocity distribution shows that the inlet flow is very chaotic. A high turbulent kinetic energy value of around 0.08 m2/s2 exists in this region, and a recirculating flow was also found here. These flow characteristics are harmful since they increase the inclusion transport toward the wall. Therefore, a new design of the SEN inlet should be developed in the future, with the aim to modify the inlet flow so that the inclusion deposition is reduced.

  • 30.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhang, T. -A
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Numerical study on the influence of a swirling flow tundish on multiphase flow and heat transfer in mold2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 5, artikkel-id 368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of a new cylindrical swirling flow tundish design on the multiphase flow and heat transfer in a mold was studied. The RSM (Reynolds stress model) and the VOF (volume of fluid) model were used to solve the steel and slag flow phenomena. The effect of the swirling flow tundish design on the temperature distribution and inclusion motion was also studied. The results show that the new tundish design significantly changed the flow behavior in the mold, compared to a conventional tundish casting. Specifically, the deep impingement jet from the SEN (Submerged Entry Nozzle) outlet disappeared in the mold, and steel with a high temperature moved towards the solidified shell due to the swirling flow effect. Steel flow velocity in the top of the mold was increased. A large velocity in the vicinity of the solidified shell was obtained. Furthermore, the risk of the slag entrainment in the mold was also estimated. With the swirling flow tundish casting, the temperature distribution became more uniform, and the dissipation of the steel superheat was accelerated. In addition, inclusion trajectories in the mold also changed, which tend to stay at the top of the mold for a time. A future study is still required to further optimize the steel flow in mold.

  • 31.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Haglund, Teodor
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Study on Slopping Prevention in the BOF Steelmaking Process2017Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, nr 8, artikkel-id UNSP 1600399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new method of preventing slopping is proposed in this paper, by simply blowing gas at the top of the foam surface. The physical experiment results show that the foam height can be effectively decreased by the top blowing air. The maximum decrease of the foam height can reach around 70 mm with an initial foam height of 145 mm in the current setup, around a 48% decrease. The first 40 mm of the foam height is easy to destroy with a low flow rate from the top. However, it is increasingly difficult for a further decrease in the foam height. Different types of nozzles show a large difference in the role of destroying the foam. The air flow velocity from the nozzle outlet is found to be the key factor for a decreased foam height. Overall, three foam destruction mechanisms are proposed. When the top air flow velocity is small, the drag and pressure destruction mechanisms are the main reasons for the decrease in foam height. However, when a large top air flow velocity is used, the coalescence and breakup mechanisms due to a high turbulence and the shear force on gas bubble shape deformation become important.

  • 32.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Swedish Defence Research Agency, Sweden.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Deposition of Particles in Liquid Flows in Horizontal Straight ChannelsManuskript (preprint) (Annet vitenskapelig)
  • 33.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Swedish Defence Research Agency, Sweden.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    The Use of an Enhanced Eulerian Deposition Model to Investigate Nozzle Clogging During Continuous Casting of Steel2014Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 45, nr 6, s. 2414-2424Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nozzle clogging caused by the build-up of non-metallic inclusions on ceramic walls is a serious industrial problem during continuous casting of steel. The current theoretical study uses the extended Eulerian model to predict the inclusion deposition rate in a submerged entry nozzle (SEN). The model considers Brownian and turbulent diffusion, turbophoresis, and thermophoresis as transportation mechanisms. First, the steel flow in a tundish was simulated using a three-dimensional CFD model. The obtained flow parameter in a SEN was then put into the Eulerian deposition model to predict the deposition rate of non-metallic inclusions. Thereafter, the deposition rates of different-size inclusions in the SEN were predicted and compared. The result shows that the steel flow is non-uniform in the SEN of the tundish. This leads to an uneven distribution of the inclusion deposition rates at different locations of the inner wall of the SEN. In addition, large size inclusions among the size of inclusions considered show a large deposition rate, due to the strong effect of turbophoresis.

  • 34.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Turbulent Flow Phenomena and Ce2O3 Behavior during a Steel Teeming Process2013Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, nr 5, s. 792-801Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Steel flow phenomena and Ce2O3 inclusion behavior are presented in this paper. A three-dimensional model was developed to describe the steel flow phenomena and the inclusion behavior during a teeming process. The Kim-Chen modified k-ɛ turbulent model was used to simulate the turbulence properties and the Height-of-Liquid model was used to capture the interface between gas and steel. A Lagranian method was then used to track the inclusions and to compare the behaviors of different-size inclusions in the steel flow. In addition, a statistical analysis was carried out by the use of a stochastic turbulence model to investigate the behaviors of different-size inclusions at different nozzle regions. The results show that the steel flow was the most turbulent at the connection part of the straight pipe part and the expanding part of the nozzle. All inclusions with a diameter smaller than 20 μm were found to have a similar trajectory and velocity distribution in the nozzle. However, inertia force and buoyancy force were found to play an important role for the behaviors of large-size inclusions/clusters. The statistical analysis results indicate that the regions close to the connection region between different angled nozzle parts seem to be very sensitive with respect to deposition of inclusions.

  • 35.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jonsson, Lage Lord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    On the deposition of particles in liquid metals onto vertical ceramic walls2014Inngår i: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 62, s. 152-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deposition of non-metallic particles in liquid-metal flows is a serious industrial problem because the build-up of particles on ceramic walls clogs the flow path and interrupts the production, and this leads to large economic losses. This paper is an effort to extend the current state-of-the-art knowledge of particle deposition in air in order to predict particle deposition rates in liquid-metal flows using an improved Eulerian deposition model and considering Brownian and turbulent diffusion, turbophoresis and thermophoresis as transportation mechanisms. The model was used to predict the rate of deposition of particles in an air flow, and the predictions were compared to published measurements to demonstrate its performance. The model was then modified to take into account the differences in properties between air and liquid metals and thereafter applied to liquid-metal flows. Effects on the deposition rate of parameters such as steel flow rate, particle diameter, particle density, wall roughness and temperature gradient near the wall were investigated. It is shown that the steel flow rate has a very important influence on the rate of deposition of large particles, for which turbophoresis is the main deposition mechanism. For small particles, both wall roughness and thermophoresis have a significant influence on the particle deposition rate. Particle deposition rates under various conditions were successfully predicted.

  • 36.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage T. I.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    The development of an eulerian deposition model in liquid metal flows and its application on nozzle clogging during continuous casting of steel2015Inngår i: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, s. 439-442Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An Eulerian deposition model was developed and used to predict the deposition rates of non-metallic inclusions in liquidmetal flows. Effects of parameters such as particle diameter, wall roughness and temperature gradient near the wall on the deposition rates were investigated. Thereafter, the modified Eulerian model was used to calculate the deposition rate of non-metallic inclusions in a tundish nozzle. Furthermore, the deposition rates of different-size inclusions in the SEN were predicted and compared. The results show that both the wall roughness and thermophoresis have a significant influence on the deposition rate of small particles. For larger inclusions, turbophoresis is the main deposition mechanism. In addition, an uneven distribution of the inclusion deposition rates at the inner wall of the SEN was observed. A large deposition rate was found at the regions near the SEN inlet, the SEN bottom and the upper region of two SEN ports.

  • 37.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage T. I.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Application of a swirling flow producer in a conventional tundish during continuous casting of steel2017Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 57, nr 12, s. 2175-2184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A swirling flow producer was designed for a conventional tundish in order to produce a swirling flow in the SEN driven by the steel flow potential. CFD simulations were carried out to investigate the flow phenomena in the new tundish system. The results show that a swirling flow in the tundish SEN was successfully obtained. The swirl number of the obtained steel flow inside the SEN can reach a value of 1.34, with a tangential velocity of around 2.8 m/s. The possibility of slag entrainment at the top of the tundish was estimated by analyzing the steel flow characteristics near the top surface. The calculated Weber Number is around 0.3 outside the cylinder, which indicates a low possibility of slag entrainment. A high value of shear stress was found on the SEN wall. This is due to the rotational steel flow in SEN. Also, non-metallic inclusions were tracked in the fully developed steel flow field. It was found that the number of inclusions that touch the top surface increases with an increased inclusion size. Small size inclusions mainly move into the cylinder from the left side of tangential inlet. Therefore, methods like installing a dam at the tundish bottom may be helpful to change the inclusion trajectories to move towards the top of the tundish.

  • 38.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Transport and Deposition of Non-Metallic Inclusions in Steel Flows- A Comparison of Different Model Predictions to Pilot Plant Experiment Data2017Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, nr 12, artikkel-id UNSP 1700155Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inclusion behavior during a ladle teeming process is investigated. A Lagrangian method is used to track different-size inclusions and to compare their behaviors in steel flows, solved by the realizable k-epsilon model with SWF (Standard Wall Function), realizable k-epsilon model with EWT (Enhanced Wall Treatment), and RSM (Reynolds Stress Model). The results show that inclusion tracking based on the realizable k-epsilon model with SWF to predict the steel flow does not agree with the data fromplant experiments. The predicted number of inclusions touching the wall shows almost no dependence on inclusion size. This is due to that the boundary layer is not resolved. The inclusion deposition predicted using the realizable k-epsilon model with EWT and the RSM model to predict the steel flow generally agrees with the experimental observations. However, the large size inclusion deposition is over-predicted when using the realizable k-epsilon model with EWT. More specifically, the prediction for 20 mu m inclusions is three times larger than that with the RSM. This is due to that this model cannot calculate the anisotropic turbulence fluctuations. In summary, the turbulence properties in the near-wall boundary layer are found to be very important for a good prediction on inclusion deposition.

  • 39.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Northeastern Univ, Peoples R China.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Deposition of particles in liquid flows in horizontal straight channels2016Inngår i: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 62, s. 166-173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A flow in a horizontal channel is an important method for the transport of materials, products and/or waste gases/liquids. The deposition of particles in a horizontal channel may clog the flow path. The purpose of this paper is to extend the use of a developed Eulerian deposition model to liquid flows in horizontal straight channels to predict the particle deposition rate. For a horizontal pipe, the deposition rates may differ greatly along a cross section, due to the influences of gravity and buoyancy. The current deposition model is first applied to air flows to enable a comparison with available experimental data. Then, the model is applied to liquid flows in horizontal straight pipes. The effects of gravity, buoyancy, water flow rates, wall roughness, particle size and temperature difference in the near-wall boundary layer on the deposition rate have been studied and explained. The results show that the deposition rates of particles increase with an increased flow rate. The gravity separation has a large influence on the deposition of large particle at high and low parts of the horizontal pipe in some flows. Moreover, both the wall roughness and thermophoresis have a significant influence on the deposition rate of small particles. In addition, the roughness also shows an important influence on the large particle deposition at the top of the investigated pipe, due to that a large value of roughness can make the deposition location somewhat far away from the wall, where a stronger turbophoresis exists. The intensity of the turbophoresis relative to the gravity separation before a particle is reaching the deposition location is important for the large particle deposition when the gravity separation play a negative role on the deposition rate. (C) 2016 Elsevier Inc. All rights reserved.

  • 40.
    Ni, Peiyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Non-Metallic Inclusion Behaviors in a New Tundish and SEN Design Using a Swirling Flow during Continuous Casting of Steel2016Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behaviors of non-metallic inclusions in a new tundish and SEN design enabling a swirling flow are investigated by using a Lagrangian particle tracking scheme. The results show that 99% of both Al2O3 and Ce2O3 inclusions are removed from both the top surface and the other tundish walls with a "trap" boundary condition, while only around 60% are removed from the top surface of tundish for a "reflect" boundary condition at the other tundish walls. Large size non-metallic inclusions of different densities show a large difference under a "reflect" boundary condition at tundish walls, due to a high buoyancy of light inclusions. In the swirling flow SEN, a much smaller number of large Al2O3 inclusions touches the wall compared to Ce2O3 inclusions. This is due to that they have larger deviations from the steel flow path compared to heavy Ce2O3 inclusions, due to the centripetal force. For small size inclusions, the centripetal separation is not effective neither for the light Al2O3 inclusions nor for the heavy Ce2O3 inclusions in the current swirling flow SEN with a swirl number of 0.4. Light Al2O3 inclusions larger than 40μm can be influenced by the current centripetal force.

  • 41.
    Ni, Peiyuan
    et al.
    Osaka Univ, Grad Sch Engn, Div Mat & Mfg Sci, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan..
    Tanaka, Toshihiro
    Osaka Univ, Grad Sch Engn, Div Mat & Mfg Sci, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan..
    Suzuki, Masanori
    Osaka Univ, Grad Sch Engn, Div Mat & Mfg Sci, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan..
    Nakamo, Masashi
    Osaka Univ, Grad Sch Engn, Div Mat & Mfg Sci, 2-1 Yamadaoka, Suita, Osaka 5650871, Japan..
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Mathematical Modelling Study of Dynamic Composition Change of Steel and Mold Flux in Continuous Casting of Steel2019Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 59, nr 11, s. 2024-2035Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A kinetic model was developed to describe multicomponent reactions and mass transfer at the steel/molten flux interface under the effect of the interfacial tension. This model mainly describes the following interfacial physicochemical phenomena: i) Silica decomposition and oxygen adsorption at the interface, ii) Oxygen and titanium reactions at the interface, iii) Oxygen and aluminum reaction at the interface, iv) Silica mass transfer from the flux bulk to the interface, and v) Dissolution of the formed titanium dioxide and alumina into the flux and its transfer in flux. With this model, the dynamic changes of the mold flux composition, steel composition, interfacial oxygen content and interfacial tension for different mold flux compositions were predicted. Overall, the dynamic composition changes of the mold fluxes in a casting mold were reproduced. The basicity of the mold flux shows a large influence on the dynamic change of its composition. The initial composition change of the mold flux is fast when the flux with a high basicity was used, compared with the case of the mold flux with a low basicity. The interfacial oxygen content and the interfacial tension were found to reach a constant value after the steel/flux reaches a metastable state. In addition, the interfacial adsorption of oxygen due to the interfacial tension effect was found to significantly accelerate the dynamic change process of the steel/mold flux system.

  • 42.
    Nilsson, Peter
    et al.
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Jonsson, L. T. I.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    A New Tundish Design to Produce a Swirling Flow in the SEN During Continuous Casting of Steel2016Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new tundish is designed with the aim to produce a swirling flow in a tundish SEN by an economical way of using the steel flow potential as the required power. This design is easily obtained by adding a cylindrical part of the tundish onto a traditional tundish. The results show that a swirling flow in the SEN of the new tundish is successfully obtained, also, that the tangential velocity in the SEN can reach around 1.6ms-1. The installation of weirs in the cylindrical tundish can contribute to stabilize the steel flow at the top of the tundish. However, this reduces the swirling flow intensity in the SEN around 30%. In addition, the possibility of slag entrainment at the top of the tundish is analyzed. The calculated Weber Number is around 5.0 for no weir case and 2.8 for the weir case, which means that the risk of slag entrainment is small. A high value of shear stress is found on the SEN wall due to the swirling flow in SEN. A further investigation shows that a smooth transition of SEN inlet can reduce the maximum shear stress level in the SEN, without decreasing the swirling flow intensity.

  • 43.
    Saffari Pour, Mohsen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Andersson, Nils Å. I.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Niska, John
    Rensgard, Anders
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    The Behavior of Impurities During Producer Gas Implementation as Alternative Fuel in Steel Reheating Furnaces: A CFD and Thermo-Chemical Study2016Inngår i: ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), USA: The American Society of Mechanical Engineers , 2016, Vol. 6A, artikkel-id V06AT08A011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of available and cheap industrial producer gases as alternative fuels for the steel reheating furnaces is an attractive topic for steel industry. The application of producer gases for such furnaces introduces not only the complicated combustion system of Low Calorific Value (LCV) gases, but also several impurities that could be problematic for the quality of final steel products. The quality of steel can be highly affected by the interaction of impurities with iron-oxides at hot slab surfaces. In this research, the combustion of producer gases and the behavior of impurities at the steel slab surface are studied by aid of a novel coupled computational fluid dynamics (CFD) and thermodynamics approach. The impurities are introduced as mineral ash particles with the particle size distributions of 15–100 μm. The CFD predicted data regarding the accumulation of ash particles are extracted from an interface layer at the flaring gas media around the steel slab surface. Later on, these predicted data are used for the thermo-chemical calculations regarding the formation of sticky solutions and stable phases at the steel slab surface. The results show that the particles are more likely follow the flow due to the high injection velocity of fuel (70 m/s) and the dominant inertial forces. More than 90 percent of particles have been evacuated through the exhaust pipes. The only 10 percent of remaining particles due to the high recirculation zones at the middle of furnace and the impinging effect of front walls tend to stick to the side wall of slab in the heating zone more than the soaking zone.

  • 44.
    Saffari Pour, Mohsen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jonsson, Lage Tord Ingemar
    Andersson, Nils
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Saffaripour, Mohammadhassan
    Shahid Bahonar University of Kerman, Kerman, Iran.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    On the Implementation of Producer Gases as Alternative Fuels in Steel Reheating Furnaces2015Inngår i: Proccedings of ASME 2015 International Mechanical Engineering Congress and Exposition / [ed] ASME, Houston, Texas, USA, November 13–19, 2015: ASME Press, 2015, Vol. 6AKonferansepaper (Fagfellevurdert)
    Abstract [en]

    During the past decades, combustion of producer gases from other facilities has been introduced as one of the promising techniques in steel furnaces. The impurities inside producer gases are responsible for a low quality steel production due to formation of the molten ash that forms sticky layers of solutions on steel surfaces. Therefore, a comprehensive investigation is needed before a full implementation of producer gases inside the industrial furnaces. In this paper, the effects of impurities inside the gasified biomass flue gases are thermodynamically investigated regarding temperature zones inside a reheating furnace. After that, the high temperature agent combustion (HiTAC) is investigated as a solution for a steel batch reheating furnace to reduce the side effects of using the producer gases. Finally, computational fluid dynamics (CFD) is used as a numerical technique to compare four different producer gases in the studied furnace. The temperature distribution is validated with existing literature data. It shows a good agreement with a 5% error in the heating and a 10% error in the soaking zones of the reheating furnace. The comparison of simulation results assists in the understanding of the chemical and thermal behavior of different gases and provides useful data for the furnace fuel optimization.

  • 45.
    Song, Zhili
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    A Study of Post Combustion in a BOF converter2013Rapport (Annet vitenskapelig)
  • 46.
    Song, Zhili
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    A study of post-combustion in an AOD flue2014Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, nr 7, s. 1173-1184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An investigation on the post-combustion phenomena in an argon oxygen decarburization (AOD) system containing a converter and a flue has been conducted. An AOD converter is mainly characterized by nozzles installed at the lower side of the converter. The nozzles are intended to inject the decarburization gas of oxygen mixed with an inert gas such as argon. The injection promotes stirring and lowers the partial pressure of CO in the converter. For the AOD converter of interest in the current work, a fan is installed in the end of the AOD flue to help extract the off-gas from the converter. The influence of different fan gauge pressures as well as temperatures of the gas mixture, containing the generated CO and argon, on the post-combustion in the whole AOD system was studied. The realizable k-epsilon model was employed as the turbulence model. In addition, the reaction and radiation were also taken into account by use of the species transport model and the discrete ordinate model. It was indicated from the modeling results that the post-combustion was only present in the flue for the present modeling conditions. Moreover, a critical fan gauge pressure was found, which could yield a maximum post-combustion in the flue gas. Finally, no obvious change on the post-combustion was shown if the inlet gas mixture temperature was varied between 1500 and 1700 degrees C.

  • 47.
    Song, Zhili
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Mathematical comparison of two VOD nozzle jets2011Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, nr 10, s. 1637-1646Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Studies of physical phenomena in a jet caused by VOD (Vacuum Oxygen Decarburization) nozzles have been carried out. The VOD process is a metallurgical process where the steel-making route is controlled under vacuum environment with oxygen top blowing. In this work, two VOD nozzle models have been employed for an investigation based on two real De Laval geometries used in industry. Numerical modeling was used to study oxygen blowing states of the nozzles at different temperatures and ambient pressures. The nozzle models were numerically computed with two dimensional domains, where vacuum conditions and temperatures were specifically defined. The modeling results showed that one of the nozzles was more applicably proper for lower pressures, displaying a more stable flow pattern. Furthermore, it was found that a change in ambient pressure has a stronger effect on the jet force than a change in ambient temperature. In addition, it was proved that the profiles of the dynamic pressure at a certain blowing distance fit well to Multi-Gaussian curves.

  • 48.
    Song, Zhili
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Mathematical Modeling of VOD Oxygen Nozzle Jets2011Inngår i: Steel Research International, ISSN 1611-3683, Vol. 82, nr 3, s. 249-259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study has focused on numerically exploring the oxygen flow in the convergent-divergent De Laval nozzle. The De Laval nozzle has been commonly used as oxygen outlet at the lance tip in the vacuum oxygen decarburization (VOD) process. The nozzle geometry used in an active VOD plant was investigated by isentropic nozzle theory as well as by numerical modeling. Since an optimal nozzle design is only valid for a certain ambient pressure, one VOD nozzle will be less efficient for a large part of the pressure cycle. Different ambient pressures were used in the calculations that were based on the De Laval nozzle theory. Flow patterns of the oxygen jet under different ambient pressures were studied and the flow information at different positions from the nozzle was analyzed. In addition, the study compared the effects of different ambient temperatures on jet velocity and dynamic pressure. The predictions revealed that the modeling results obtained with the CFD modeling showed incorrect flow expansion, which agreed well with the results from the De Laval theory. Moreover, a little under-expansion is somewhat helpful to improve the dynamic pressure. The jet dynamic pressure and its width for the specific nozzle geometry have also been studied. It has been observed that an altering ambient pressure can influence the jet momentum and its width. In addition, a high ambient temperature has a positive effect on the improvement of the jet dynamic pressure.

  • 49.
    Tan, Zhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Effect of TurboSwirl on Inclusions during Ingot Casting of Steels2015Inngår i: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, artikkel-id 805734Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of TurboSwirl to obtain an improved steel cleanliness during filling of an ingot was numerically studied by VOF and DPM models. It was found that a radius-reduced TurboSwirl or a proper tapered mold entrance nozzle with an adequate developed region for steel flow can reduce the risk of mold flux entrapment in a mold. The ingot casting process can create highly turbulent conditions inside the mold during the initial stages of casting. Since the TurboSwirl generates much calmer filling conditions it can promote separation of large nonmetallic inclusions. The TurboSwirl also collects large inclusions (200 mu m) towards the axis of rotation, which should promote agglomeration. In addition, the residence time for inclusions of small sizes can be prolonged, increasing chance of agglomeration, which indirectly promotes their separation from steel. Moreover, the average turbulent dissipation rate in an ingot casting swirl setup is about 40 % higher than that in a no swirl setup. This further facilitates the agglomeration of inclusions before they enter the mold. The removal of nonmetallic inclusions is thus enhanced because of an increasing inclusion collision rate due to both Stokes collisions and turbulent collisions, while maintaining a calm flow inside the mold.

  • 50.
    Tan, Zhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Effect of TurboSwirl on Steel Cleanliness during Ingot FillingManuskript (preprint) (Annet vitenskapelig)
12 1 - 50 of 72
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