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Lu, Y.-C., Karasev, A. & Ersson, M. (2023). Direct Reduction of Iron Ore Pellets by Using CO/CO2 and CO Gases. Steel Research International, 95(3)
Open this publication in new window or tab >>Direct Reduction of Iron Ore Pellets by Using CO/CO2 and CO Gases
2023 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 95, no 3Article in journal (Refereed) Published
Abstract [en]

Gas-based direct reduction in a shaft furnace is the dominant process in the world for production of direct reduced iron. As fresh reducing gas passes through the iron ore burden, it is diluted by the gas emitted from the reacted iron ores which decreases the reduction potential of the reducing gas. Previous reduction experiments mostly used single pellet which could not examine this phenomenon. In this study, hematite pellets arranged in multiple layers inside a molybdenum basket are reduced isothermally at 1173–1273 K using 50% CO + 50% CO2% and 100% CO gases under flow rates of 0.2–5.0 NL min−1 to simulate the dilution of CO by CO2 in the shaft. It is discovered that the reduction of pellets in the basket is highly uneven even in pure CO atmosphere. Pellets in the middle layer are reduced ≈2 times less than the pellets in the top and bottom layers. The top side of a pellet is also less reduced than the bottom side facing the gas inlet. During melting of incompletely reduced pellets at 1873 K, intensive interaction between the unreduced iron oxides and the alumina crucible was observed. Thus, smelting of incompletely reduced iron could potentially shorten the refractory lifetime.

Place, publisher, year, edition, pages
Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2023
Keywords
carbon monoxide, direct reduced iron, incompletely reduced iron, iron ore pellet, low CO2 steelmaking
National Category
Metallurgy and Metallic Materials
Research subject
Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-345650 (URN)10.1002/srin.202300634 (DOI)001134496800001 ()2-s2.0-85180849422 (Scopus ID)
Projects
OSMET 3.0
Funder
Vinnova, 2021‐04660
Note

QC 20240416

Available from: 2024-04-16 Created: 2024-04-16 Last updated: 2024-04-26Bibliographically approved
Wang, J., Ni, P., Chen, C., Ersson, M. & Li, Y. (2023). Effect of gas blowing nozzle angle on multiphase flow and mass transfer during RH refining process. International Journal of Minerals, Metallurgy and Materials, 30(5), 844-856
Open this publication in new window or tab >>Effect of gas blowing nozzle angle on multiphase flow and mass transfer during RH refining process
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2023 (English)In: International Journal of Minerals, Metallurgy and Materials, ISSN 1674-4799, E-ISSN 1869-103X, Vol. 30, no 5, p. 844-856Article in journal (Refereed) Published
Abstract [en]

A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow, circulation flow rate, and mixing time during Ruhrstahl-Heraeus (RH) refining process. Also, a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up, and measurements were carried out to validate the mathematical model. The results show that, with a conventional gas blowing nozzle and the total gas flow rate of 40 L center dot min(-1), the mixing time predicted by the mathematical model agrees well with the measured values. The deviations between the model predictions and the measured values are in the range of about 1.3%-7.3% at the selected three monitoring locations, where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value. In addition, the circulation flow rate was 9 kg center dot s(-1). When the gas blowing nozzle was horizontally rotated by either 30 degrees or 45 degrees, the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle, due to the rotational flow formed in the up-snorkel. Furthermore, the mixing time at the monitoring point 1, 2, and 3 was shortened by around 21.3%, 28.2%, and 12.3%, respectively. With the nozzle angle of 30 degrees and 45 degrees, the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Ruhrstahl-Heraeus refining, gas blowing nozzle angle, circulation flow rate, mixing time, multiphase flow
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-324402 (URN)10.1007/s12613-022-2558-5 (DOI)000920071100006 ()2-s2.0-85146794851 (Scopus ID)
Note

QC 20230301

Available from: 2023-03-01 Created: 2023-03-01 Last updated: 2023-03-01Bibliographically approved
Xie, Q. h., Ni, P. y., Tanaka, T., Ersson, M. & Li, Y. (2023). Flow field, heat transfer and inclusion behavior in a round bloom mold under effect of a swirling flow submerged entry nozzle. Journal of Iron and Steel Research International, 30(6), 1211-1221
Open this publication in new window or tab >>Flow field, heat transfer and inclusion behavior in a round bloom mold under effect of a swirling flow submerged entry nozzle
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2023 (English)In: Journal of Iron and Steel Research International, ISSN 1006-706X, E-ISSN 2210-3988, Vol. 30, no 6, p. 1211-1221Article in journal (Refereed) Published
Abstract [en]

Flow field, heat transfer and inclusion behavior in a 700 mm round bloom mold under the effect of a swirling flow submerged entry nozzle (SEN) were investigated with the aim to enhance the casting process. The results indicate that the impinging flow phenomenon, which is commonly observed in conventional single-port SEN casting, was completely suppressed by the swirling flow SEN coming from a novel swirling flow generator design in tundish. Steel from the SEN port moved towards the mold wall in 360° direction, leading to a uniform temperature distribution in the mold. Compared to a conventional single-port SEN casting, the steel super-heat was decreased by about 5 K at the mold center, and the temperature was increased by around 3.5 K near the meniscus. In addition, the removal ratio of inclusions to the mold top surface in the swirling flow SEN casting was found to be increased. Specifically, the removal ratio of spherical inclusions with diameters of 1, 10, 50 and 100 μm was increased by 18.2%, 18.5%, 22.6% and 42.7%, respectively. Furthermore, the ratio was raised by 18.2%, 20.8%, 21.5% and 44.1% for non-spherical inclusions, respectively.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Flow field, Heat transfer, Inclusion behavior, Large round bloom, Swirling flow submerged entry nozzle casting
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-331539 (URN)10.1007/s42243-023-00975-9 (DOI)000995312300001 ()2-s2.0-85160337187 (Scopus ID)
Note

QC 20230711

Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-07-11Bibliographically approved
Wang, J., Ni, P., Zhou, X., Liu, Q., Ersson, M. & Li, Y. (2023). Study on Multiphase Flow Characteristics During RH Refining Process Affected by Nonradial Arrangement of Gas-Blowing Nozzle. Steel Research International, 94(12), Article ID 2300200.
Open this publication in new window or tab >>Study on Multiphase Flow Characteristics During RH Refining Process Affected by Nonradial Arrangement of Gas-Blowing Nozzle
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2023 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 94, no 12, article id 2300200Article in journal (Refereed) Published
Abstract [en]

Bath stirring, degassing, and decarburization in steel refining are strongly related to flow behaviors. The bubble plume produced in Ruhrstahl–Heraeus (RH) up-snorkel plays an important role during refining, since it not only acts as a bubble pump, but also provides the reaction interface. Herein, it is aimed to form a new flow pattern in the up-snorkel by using a nonradially arranged gas-injection nozzle to enhance the 260 ton RH refining process. The results show that an upward spiral steel flow is produced, when nonradial gas-injection nozzles are used in the up-snorkel. Meanwhile, some bubbles moved toward the center region of the up-snorkel, which may be caused by the centripetal effect in a rotational steel flow. This leads to a more uniform bubble distribution on the cross section of the snorkel, compared to that of the conventional case. Specifically, the circulation flow rate is increased by about 18.0%, and the mixing time are shortened by about 26.2% (criteria of ±5%), compared to that of the conventional case. In addition, the inclusion removal rate is increased by 0.5%, 4.8%, and 11.3% for the inclusion size of 20, 50, and 100 μm, respectively, compared to the conventional radial nozzle case.

Place, publisher, year, edition, pages
Wiley, 2023
Keywords
mixing time, multiphase flows, nonradial gas injection, RH refining, rotational up-snorkel flows
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-348449 (URN)10.1002/srin.202300200 (DOI)001047737000001 ()2-s2.0-85167706001 (Scopus ID)
Note

QC 20240624

Available from: 2024-06-24 Created: 2024-06-24 Last updated: 2024-06-24Bibliographically approved
Chanouian, S., Larsson, H. & Ersson, M. (2023). The Importance of Mixing Time in Intensely Stirred Metallurgical Reactors: Applied on Decarburization Reactions. Metals, 13(10), Article ID 1694.
Open this publication in new window or tab >>The Importance of Mixing Time in Intensely Stirred Metallurgical Reactors: Applied on Decarburization Reactions
2023 (English)In: Metals, ISSN 2075-4701, Metals, E-ISSN 2075-4701, Vol. 13, no 10, article id 1694Article in journal (Refereed) Published
Abstract [en]

In metallurgical converter processes, numerical modeling is a useful tool for understanding the complexity of the systems. In this paper, we present a practical model that couples fluid dynamics and chemical reactions to explore the impact of mixing time on decarburization. Using computational fluid dynamics (CFD), in this study, we investigate an arbitrary metallurgical reactor with continuous oxygen supply, focusing on the Fe–C–O system. The model employs local equilibrium, a turbulence limiter, and finite volume method for mass, momentum, and energy transfer. Tracer injection points in the gas plume’s rising region exhibit faster mixing, and a comparison of reaction cases reveals distinct decarburization rates based on oxygen injection distribution and the influence of turbulence on reactions. Overall, while mixing time matters, the results show that this system is primarily governed by thermodynamics and oxygen supply, and a 270% increase in mixing time increase had a small impact on the end carbon content.

Place, publisher, year, edition, pages
MDPI AG, 2023
Keywords
mixing time, decarburization, metallurgical processes, computational fluid dynamics
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-338884 (URN)10.3390/met13101694 (DOI)001089525700001 ()2-s2.0-85175043629 (Scopus ID)
Funder
Vinnova, 2018-02386
Note

QC 20231030

Available from: 2023-10-30 Created: 2023-10-30 Last updated: 2023-11-21Bibliographically approved
Chanouian, S., Ahlin, B., Tilliander, A. & Ersson, M. (2022). A Fundamental Investigation of Decarburization Reactions in the Argon–Oxygen Decarburization Converter Using Coupled Computational Fluid Dynamics and Thermodynamics Databases. Steel Research International, 93(12), Article ID 2200156.
Open this publication in new window or tab >>A Fundamental Investigation of Decarburization Reactions in the Argon–Oxygen Decarburization Converter Using Coupled Computational Fluid Dynamics and Thermodynamics Databases
2022 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 93, no 12, article id 2200156Article in journal (Refereed) Published
Abstract [en]

Metallurgical converters such as the argon–oxygen decarburization (AOD) converter generally utilize gas blowing for the mixing and refinement of liquid steel. Due to the harsh environment of the complex and opaque system, it is common practice to study the stirring of the process through physical and numerical models. Effective mixing in the bath has an important role in refinement such as decarburization and has been vividly studied before. However, high-temperature chemical reactions that also play a major role are sparsely investigated. With the help of modeling, a computational fluid dynamics model coupled with chemical reactions is developed, allowing the study of both dynamic fluid transport and chemical reactions. Herein, the chemical reactions for a single gas bubble in the AOD are investigated. The study shows that a 60 mm oxygen gas bubble rapidly reacts with the melt and is saturated with carbon in 0.2–0.25 s at low-pressure levels. The saturation time is affected by the pressure and the composition of the injected gas bubble. The impact of ferrostatic pressure on the reactions is more significant at larger depth differences. 

Place, publisher, year, edition, pages
John Wiley and Sons Inc, 2022
Keywords
argon–oxygen decarburization process, bubbles, computational fluid dynamics, coupled models, decarburization reactions, Argon, Bubble formation, Chemical reactions, Decarburization, Mixing, Oxygen, Thermodynamics, Transport properties, Argon oxygen decarburization converters, Argon-oxygen decarburizations, Bubble, Decarburization reaction, Dynamic database, Harsh environment, Liquid steels, Thermodynamic database
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-325065 (URN)10.1002/srin.202200156 (DOI)000818827800001 ()2-s2.0-85133043913 (Scopus ID)
Note

QC 20230328

Available from: 2023-03-28 Created: 2023-03-28 Last updated: 2023-11-21Bibliographically approved
Xie, Q., Nabeel, M., Ersson, M. & Ni, P. (2022). A Review on Swirling Flow Casting Technology in Steel Production. Steel Research International, 93(1), Article ID 2100410.
Open this publication in new window or tab >>A Review on Swirling Flow Casting Technology in Steel Production
2022 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 93, no 1, article id 2100410Article in journal (Refereed) Published
Abstract [en]

Casting is a vital process in steel production where solidification process of molten steel occurs in mold coupled with fluid flow, heat transfer, crystal growth, inclusion motion, solute redistribution, segregation, and so on. All these phenomena are closely related to the steel flow behavior. To optimize the flow field in mold at initial moment, the swirling flow casting technology is developed and has received extensive attention in past years. It is believed to be a promising method to further optimize the steel flow and to improve the solidification process. Herein, the swirling flow steel casting is comprehensively reviewed to introduce different realization technologies, new research progress, and the current situation of their application. This aims to promote the development and usage of swirling flow technology in steel casting. 

Place, publisher, year, edition, pages
Wiley, 2022
Keywords
Continuous casting, Heat transfer, Molds, Solidification, Steel castings, Steel foundry practice, Casting technology, Continous casting, Fluid-flow, Inclusion motion, Ingot casting, Molten steel, Solidification process, Steel flow, Steel production, Swirling flow nozzle, Swirling flow
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-312040 (URN)10.1002/srin.202100410 (DOI)000702442500001 ()2-s2.0-85115993364 (Scopus ID)
Note

QC 20220516

Available from: 2022-05-16 Created: 2022-05-16 Last updated: 2022-06-25Bibliographically approved
Zhou, X., Zhang, Y., He, Q., Ni, P., Yue, Q. & Ersson, M. (2022). Novel Evaluation Method to Determine the Mixing Time in a Ladle Refining Process. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 53(6), 4114-4123
Open this publication in new window or tab >>Novel Evaluation Method to Determine the Mixing Time in a Ladle Refining Process
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2022 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 53, no 6, p. 4114-4123Article in journal (Refereed) Published
Abstract [en]

Mixing plays a key role in mass and heat transfer, as well as chemical reactions in various vessels involving agitation. Several studies have confirmed that the mixing time obtained from several monitor locations cannot reflect the mixing time for the whole bath because stirring situation in different locations is variable due to the change of operation schemes. It is proved that some zones with inefficient stirring cannot be monitored by applying a limited amount of probes in physical and mathematical models. This study provides a novel approach to quantify mixing time evaluation considering the tracer variation for the whole bath using a mathematical model. It was found that the mixing time obtained by considering the whole bath is more representative than that of the probe monitor method. Compared with the traditional probe method, about 50 to 70 pct longer mixing times were obtained for different operations by applying the volume track method. In addition, the volume integral of the concerned variable for the whole bath is more representative to determine the developed flow compared to the points monitoring method for a transient simulation. 

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Heat transfer, Mixing, Evaluation methods, Ladle refining, Mass and heat transfers, Mixing time, Monitor location, Monitoring methods, Operation schemes, Probe methods, Refining process, Volume integrals, Probes
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-328825 (URN)10.1007/s11663-022-02671-7 (DOI)000871829600001 ()2-s2.0-85140595059 (Scopus ID)
Note

QC 20230613

Available from: 2023-06-13 Created: 2023-06-13 Last updated: 2023-06-13Bibliographically approved
Xie, Q., Ni, P., Ersson, M., Jönsson, P. & Li, Y. (2022). Numerical Simulations on Dynamic Behavior of Multiphase Flow and Heat Transfer in a Round Mold with a Swirling Flow Tundish Design. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 53(5), 3197-3214
Open this publication in new window or tab >>Numerical Simulations on Dynamic Behavior of Multiphase Flow and Heat Transfer in a Round Mold with a Swirling Flow Tundish Design
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2022 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 53, no 5, p. 3197-3214Article in journal (Refereed) Published
Abstract [en]

Three-dimensional computational fluid dynamics simulations were carried out to investigate the multiphase flow and heat transfer in a round mold, when using swirling flow generator (SFG) designs in a tundish. The results show that an impinging flow in the mold is significantly suppressed by using a SFG design, compared to when using a conventional tundish. This is due to the rotational flow momentum, which forces the steel to move toward the mold wall. When using SFG designs, the whole flow field shows periodic characteristics in transient simulations. At a given casting speed, the velocity fluctuation period and fluctuation range in the submerged entry nozzle depend on the SFG inlet area as well as the inlet velocity. As the inlet velocity increases from 0.185 to 0.37 m/s (inlet area decreases from 0.0048 to 0.0024 m2), the velocity fluctuation period decreases from 3 to 2 seconds and the fluctuation range increases from ± 10.5 to ± 18.2 pct. However, a symmetrical distribution of the flow field is obtained in the time-averaged results of 9 and 6 seconds intervals for SFG inlet velocities of 0.185 and 0.37 m/s, respectively. In addition, within one velocity fluctuation period, the time-averaged temperature field generally has a uniform distribution. As the SFG inlet velocity increases from 0.185 to 0.37 m/s, the steel super-heat further decreases in the mold and the temperature is increased by around 2 K near the meniscus. Finally, in the current mold with a diameter of only 150 mm, the removal ratio of inclusions to the mold top surface is low by using both SFG designs. The removal ratio of 10 μm spherical inclusions is 10 pct lower compared to when using a conventional tundish.

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Computational fluid dynamics, Flow fields, Heat transfer, Inlet flow, Molds, Multiphase flow, Velocity, Dynamic behaviors, Flow and heat transfer, Generator design, Inlet velocity, ON dynamics, Removal ratios, Swirling flow tundish, Time-averaged, Tundish, Velocity fluctuations, Swirling flow
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-326458 (URN)10.1007/s11663-022-02599-y (DOI)000836516200001 ()2-s2.0-85135480548 (Scopus ID)
Note

QC 20230508

Available from: 2023-05-08 Created: 2023-05-08 Last updated: 2023-05-08Bibliographically approved
Svantesson, J., Ersson, M. & Jönsson, P. (2021). Effect of Froude Number on Submerged Gas Blowing Characteristics. Materials, 14(3), Article ID 627.
Open this publication in new window or tab >>Effect of Froude Number on Submerged Gas Blowing Characteristics
2021 (English)In: Materials, E-ISSN 1996-1944, Vol. 14, no 3, article id 627Article in journal (Refereed) Published
Abstract [en]

The flow behavior of gas in compressible and incompressible systems was investigated at an ambient temperature in an air-water system and at an operating process temperature in the IronArc system, using computational fluid dynamics. The simulation results were verified by experiments in the air-water system and established empirical equations to enable reliable predictions of the penetration length. The simulations in the air-water system were found to replicate the experimental behavior using both the incompressible and compressible models, with only small deviations of 7-8%. A lower requirement for the modified Froude number of the gas blowing to produce a jetting behavior was also found. For gas blowing below the required modified Froude number, the results illustrate that the gas will form large pulsating bubbles instead of a steady jet, which causes the empirical equation calculations to severely underpredict the penetration length. The lower modified Froude number limit was also found to be system dependent and to have an approximate value of 300 for the studied IronArc system. For submerged blowing applications, it was found that it is important to ensure sufficiently high modified Froude numbers of the gas blowing. Then, the gas penetration length will remain stable as a jet and it will be possible to predict the values using empirical equations.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
compressible flow, incompressible flow, IronArc, OpenFOAM, modified Froude number, submerged gas blowing, gas jetting
National Category
Fluid Mechanics and Acoustics Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-292714 (URN)10.3390/ma14030627 (DOI)000615406000001 ()33573038 (PubMedID)2-s2.0-85100103432 (Scopus ID)
Note

QC 20210413

Available from: 2021-04-13 Created: 2021-04-13 Last updated: 2024-07-04Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-4384-7984

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