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Publications (8 of 8) Show all publications
Lundkvist, N., Ni, P., Iguchi, M., Tilliander, A. & Jönsson, P. (2018). A Physical Modeling Study on Slag Behavior in the AOD Converter Process. Steel Research International, 89(6), Article ID 1700536.
Open this publication in new window or tab >>A Physical Modeling Study on Slag Behavior in the AOD Converter Process
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2018 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, no 6, article id 1700536Article in journal (Refereed) Published
Abstract [en]

A water/oil physical model is built up to investigate the slag behavior under the side gas-blowing condition of an AOD process. The critical side-blowing air flow rates for the top oil entrainment and emulsification are investigated. In addition, the oil entrainment with the existence of solid particles is studied. Specifically, the influences of the tuyere size, oil viscosity, oil thickness, and volume fraction of solid particles in oil on the mixing phenomena are studied. It is found that oil viscosity is an important factor for the initial oil entrainment and emulsification. Oil thickness only has a slight influence on these phenomena. The critical air flow rate for both initial oil entrainment and emulsification increases slightly with an increased tuyere size from 2.0 to 3.2 mm. Empirical equations have been proposed to predict the critical air flow rate for the initial oil entrainment and emulsification. Furthermore, solid particles in oil are found to increase the critical air flow rate for an initial entrainment. This may be due to the increase of oil viscosity when solid particles exist in oil. In addition, a new model is developed to predict the oil viscosity when solid particles exist inside it.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
AOD, Emulsification, Entrainment, Physical modeling, Slag viscosity
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-231210 (URN)10.1002/srin.201700536 (DOI)000434279200007 ()2-s2.0-85044857849 (Scopus ID)
Note

QC 20180628

Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2018-06-28Bibliographically approved
Ternstedt, P., Ni, P., Lundqvist, N., Tilliander, A. & Jönsson, P. G. (2018). A physical modelling study to determine the influence of slag on the fluid flow in the AOD converter process. Ironmaking & steelmaking, 45(10), 944-950
Open this publication in new window or tab >>A physical modelling study to determine the influence of slag on the fluid flow in the AOD converter process
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2018 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 45, no 10, p. 944-950Article in journal (Refereed) Published
Abstract [en]

A 1:4.6 scale physical model of a production argon oxygen decarburisation (AOD) converter was used to study the influence of top slag on the AOD process. Specifically, the gas penetration depth, fluid flow and slag behaviour under different nozzle diameters, nozzle numbers and gas flow rates were studied. The results show that the relative gas penetration depth generally increases linearly with an increased gas flow rate and a decreased nozzle size. Furthermore, the slag thickness increases linearly with an increased gas flow rate. In addition, the open-eye size was found to increase exponentially with an increased gas flow rate. Overall, three kinds of fluid flow patterns were found in the experiments: (i) a counter-clockwise rotation, (ii) a clockwise rotation and (iii) a double circulation with the plume in the middle of the converter. A counter-clockwise rotation was most common for the current experimental conditions.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Physical modelling, AOD, slag, side-gas injection, penetration depth
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-240764 (URN)10.1080/03019233.2017.1415012 (DOI)000453823900014 ()2-s2.0-85039167810 (Scopus ID)
Note

QC 20190107

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Ni, P., Ersson, M., Jonsson, L. T. & Jönsson, P. (2018). A study on the nonmetallic inclusion motions in a swirling flow submerged entry nozzle in a new cylindrical tundish design. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 49(2), 723-736
Open this publication in new window or tab >>A study on the nonmetallic inclusion motions in a swirling flow submerged entry nozzle in a new cylindrical tundish design
2018 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 49, no 2, p. 723-736Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-238356 (URN)10.1007/s11663-017-1162-y (DOI)000426808500024 ()2-s2.0-85047456102 (Scopus ID)
Note

QC 20181113

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Ni, P., Ersson, M., Jonsson, L. T., Zhang, T.-A. -. & Jönsson, P. (2018). Numerical study on the influence of a swirling flow tundish on multiphase flow and heat transfer in mold. Metals, 8(5), Article ID 368.
Open this publication in new window or tab >>Numerical study on the influence of a swirling flow tundish on multiphase flow and heat transfer in mold
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2018 (English)In: Metals, ISSN 2075-4701, Vol. 8, no 5, article id 368Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI AG, 2018
Keywords
Continuous casting, Heat transfer, Mold, Multiphase flow, Swirling flow tundish
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-238229 (URN)10.3390/met8050368 (DOI)000435109300078 ()2-s2.0-85047458135 (Scopus ID)
Note

QC 20181114

Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2018-11-14Bibliographically approved
Bölke, K., Ersson, M., Ni, P., Swartling, M. & Jönsson, P. (2018). Physical Modeling Study on the Mixing in the New IronArc Process. Steel Research International, 89(7), Article ID 1700555.
Open this publication in new window or tab >>Physical Modeling Study on the Mixing in the New IronArc Process
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2018 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, no 7, article id 1700555Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
Blast Furnace, CO2 Reduction, IronArc Process, Ironmaking, Mixing, Pig Iron Production
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-232398 (URN)10.1002/srin.201700555 (DOI)000437843900001 ()2-s2.0-85044956607 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180726

Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26Bibliographically approved
Ni, P., Haglund, T. & Ersson, M. (2017). Study on Slopping Prevention in the BOF Steelmaking Process. Steel Research International, 88(8), Article ID UNSP 1600399.
Open this publication in new window or tab >>Study on Slopping Prevention in the BOF Steelmaking Process
2017 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 8, article id UNSP 1600399Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
Keywords
slag foaming, physical experiment, BOF, slopping prevention, gas rupture
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-212335 (URN)10.1002/srin.201600399 (DOI)000406720700005 ()2-s2.0-85009997088 (Scopus ID)
Note

QC 20170823

Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2017-11-13Bibliographically approved
Ni, P., Jonsson, L. T., Ersson, M. & Jönsson, P. (2017). Transport and Deposition of Non-Metallic Inclusions in Steel Flows- A Comparison of Different Model Predictions to Pilot Plant Experiment Data. Steel Research International, 88(12), Article ID UNSP 1700155.
Open this publication in new window or tab >>Transport and Deposition of Non-Metallic Inclusions in Steel Flows- A Comparison of Different Model Predictions to Pilot Plant Experiment Data
2017 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 12, article id UNSP 1700155Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-220620 (URN)10.1002/srin.201700155 (DOI)000417137300008 ()2-s2.0-85026291363 (Scopus ID)
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-01-12Bibliographically approved
Ni, P., Jonsson, L. T., Ersson, M. & Jönsson, P. G. (2016). Deposition of particles in liquid flows in horizontal straight channels. International Journal of Heat and Fluid Flow, 62, 166-173
Open this publication in new window or tab >>Deposition of particles in liquid flows in horizontal straight channels
2016 (English)In: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 62, p. 166-173Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Particle deposition, Liquid flow, Turbulent flow, Eulerian deposition model, Straight channel
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-202452 (URN)10.1016/j.ijheatfluidflow.2016.11.004 (DOI)000391780500004 ()2-s2.0-85002252549 (Scopus ID)
Note

QC 20170303

Available from: 2017-03-03 Created: 2017-03-03 Last updated: 2017-11-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1203-0181

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