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Physical modeling of a sampler filling for molten steel
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.ORCID iD: 0000-0003-1919-9964
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
2009 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 49, no 10, 1522-1529 p.Article in journal (Refereed) Published
Abstract [en]

In recent years, much attention has been paid to determining not only the composition, but also the inclusion characteristics from liquid steel samples extracted from a ladle or a tundish. Here, a crucial point is that the steel sampler is filled and solidified without changing the inclusion characteristics that exist at steel making temperatures. Therefore, one of the first steps to investigate is the flow pattern inside samplers during filling in order to obtain a more in-depth knowledge of the sampling process. In this paper, this is done using physical modeling of a lollipop-shaped sampler. More specifically, particle image velocimetry was employed to capture the flow field and calculate the velocity vectors during the entire experiment. The filling rate at the pin part of the sampler was varied during the experiments. It was found that due to the geometry change at the transition from the inlet pin to the body part of the sampler, the flow is very chaotic at the initial filling stage. Furthermore, vortexes are formed in the water sampler vessel during all the fillings and the height of the vortex center varies with the filling rate. Overall, it was found that the flow patterns in the lollipop-shaped sampler vessel can be characterized into three distinct flow regions: the upper vortexes region, the lower horizontal flow region and the middle nozzle flow region.

Place, publisher, year, edition, pages
2009. Vol. 49, no 10, 1522-1529 p.
Keyword [en]
Flow pattern, Physical modeling, PIV, Sampler, Vortex
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-24398DOI: 10.2355/isijinternational.49.1522ISI: 000271176100009Scopus ID: 2-s2.0-73949145212OAI: oai:DiVA.org:kth-24398DiVA: diva2:349514
Note
QC 20100907. Tidigare titel “Physical Modeling of a Sampler Filling”.Available from: 2010-09-07 Created: 2010-09-07 Last updated: 2017-12-12Bibliographically approved
In thesis
1. On the Study of a Liquid Steel Sampling Process
Open this publication in new window or tab >>On the Study of a Liquid Steel Sampling Process
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The liquid steel sampling method is one of the commonly used procedures in monitoring the steelmaking process. Besides it can be used for analyzing the dissolved alloys, hydrogen content and oxygen content, it can be also employed to monitor the inclusion characteristics at the steelmakings. Here, a crucial point is that the steel sampler should be filled and the metal solidifies without changing the inclusion characteristics. Therefore, the objective of this work is to fundamentally understand the liquid steel sampling process by means of analyzing and modeling the two-phase flow during the sampler filling process, and verifying the mathematical model by using the experimental data.

The present dissertation presents an experimental and theoretical study of the filling process of both the lollipop-shaped sampler and the rectangular-shaped sampler. Firstly, a physical modeling by using a water model has been carried out to fundamentally investigate the flow pattern inside the sampler vessels during its filling. The flow patterns were obtained by a PIV system. Then, a mathematical model has been built to theoretically understand the phenomena. The commercial CFD code was used. Here, different turbulence model have been compared between the realizable k-ε turbulence model and Wilcox k-ω turbulence model. It concludes that the Wilcox k-ω turbulence model agrees well with the PIV measurements.HH

Thus, the preferred it was further employed to predict the turbulent flow inside the production lollipop-shaped sampler fillings. It is important to find that the average collision volume in the production steel sampler without solidification at filling is about 30 times higher than that in a ladle furnace.

In the end, the whole sampling system was modeled. The initial solidification during the filling was taken into account. Focus was on the influence of the initial solidification on the inclusion concentrations. A discrete phase model was used to simulate the movement of inclusions in the liquid steel. Some selected different sized primary inclusions that exist in the ladles at a steelmaking process were simulated.

The same method of studying the filling procedure of the lollipop-shaped sampler was further applied to comprehensively investigate the rectangular-shaped sampler.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 47 p.
National Category
Metallurgy and Metallic Materials Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-24385 (URN)978-91-7415-704-8 (ISBN)
Public defence
2010-09-17, Salongen KTHB, Osquars Backe 31,KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100908Available from: 2010-09-08 Created: 2010-09-07 Last updated: 2012-02-24Bibliographically approved
2. A study of flow fields during filling of a sampler
Open this publication in new window or tab >>A study of flow fields during filling of a sampler
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

More and more attention has been paid to decreasing the number and size of non-metallic inclusions existing in the final products recently in steel industries. Therefore, more efforts have been made to monitor the inclusions' size distributions during the metallurgy process, especially at the secondary steelmaking period. A liquid sampling procedure is one of the commonly applied methods that monitoring the inclusion size distribution in ladles, for example, during the secondary steelmaking. Here, a crucial point is that the steel sampler should be filled and solidified without changing the inclusion characteristics that exist at steel making temperatures. In order to preserve the original size and distributions in the extracted samples, it is important to avoid their collisions and coagulations inside samplers during filling. Therefore, one of the first steps to investigate is the flow pattern inside samplers during filling in order to obtain a more in-depth knowledge of the sampling process to make sure that the influence is minimized.

The main objective of this work is to fundamentally study the above mentioned sampler filling process. A production sampler employed in the industries has been scaled-up according to the similarity of Froude Number in the experimental study. A Particle Image Velocimetry (PIV) was used to capture the flow field and calculate the velocity vectors during the entire experiment. Also, a mathematical model has been developed to have an in-depth investigate of the flow pattern in side the sampler during its filling. Two different turbulence models were applied in the numerical study, the realizable k-ε model and Wilcox k-ω model. The predictions were compared to experimental results obtained by the PIV measurements. Furthermore, it was illustrated that there is a fairly good agreement between the measurements obtained by PIV and calculations predicted by the Wilcox k-ω model. Thus, it is concluded that the Wilcox k-ω model can be used in the future to predict the filling of steel samplers.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 34 p.
Series
KTH/MSE--09/19--SE+APRMETU/AVH
Keyword
physical modeling, flow pattern, vortex, filling, PIV, sampler, simulation, turbulence, Wilcox k-ω model
National Category
Materials Engineering Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-10693 (URN)978-91-7415-330-9 (ISBN)
Presentation
2009-06-02, B23, KTH, Brinellvägen 23, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2009-06-30 Created: 2009-06-26 Last updated: 2010-11-03Bibliographically approved

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