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Mathematical and physical simulation of a top blown converter
Institute of Ferrous Metallurgy, Northeastern University, Shenyang, China.ORCID iD: 0000-0001-6212-7662
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
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2014 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, no 2, 273-281 p.Article in journal (Refereed) Published
Abstract [en]

A mathematical model of a top blown converter, which was based on a physical model of a 30 t vessel, was developed in this study. A simplified model consisting of the converter was used in the mathematical simulation. With the simplified model, it is possible to run a large number of tracer calculations within a short time, compared to solving for the entire flow evolution each time. A cavity depth and radius comparison has been done between the physical model and the mathematical model, which showed a good relative difference of 2.5% and 6.1% for the cavity depth and radius, respectively. The velocity change in the bath of the converter was monitored by setting several monitoring points in the physical model. A fully developed flow field was assumed to occur when the fluctuations in these points were small or periodic. It took approximately 25 s to get a developed flow field. In addition, the predicted mixing time showed a good relative difference of 2.8% in comparison to the experimental data. A simplified model consisting of the converter has been used in the mathematical simulation. The comparison between the physical model and the mathematical model shows that the simplified top blown model can successfully be used to calculate long-time simulations, and the mixing time calculations in frozen field can save a large amount of time compared to the simulation time using a transient flow field.

Place, publisher, year, edition, pages
2014. Vol. 85, no 2, 273-281 p.
Keyword [en]
converter, mixing time, cavity, simplified model, top blown
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-142979DOI: 10.1002/srin.201300310ISI: 000331948200011Scopus ID: 2-s2.0-84893635768OAI: oai:DiVA.org:kth-142979DiVA: diva2:705195
Note

QC 20140314

Available from: 2014-03-14 Created: 2014-03-14 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Mathematical and Physical Simulation of a BOF Converter
Open this publication in new window or tab >>Mathematical and Physical Simulation of a BOF Converter
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 29 p.
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-150413 (URN)978-91-7595-226-0 (ISBN)
Presentation
2014-09-25, Sal Sefström M131, Brinellvägen 23, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2014-09-08 Created: 2014-09-03 Last updated: 2014-11-21Bibliographically approved
2. Mathematical and Physical Simulations of BOF Converters
Open this publication in new window or tab >>Mathematical and Physical Simulations of BOF Converters
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of this study is to develop mathematical models to explore the mixing and its related phenomena in converter bath. Specifically, first, a mathematical model of a physical model converter, which was scaled down to 1/6th of a 30 t vessel, was developed in this study. A number of parameters were studied and their effects on the mixing time were recorded in a top blown converter. Second, a mathematical model for a combined top-bottom blown was built to investigate the optimization process. Then, a side tuyere was introduced in the combined top-bottom blown converter and its effects on the mixing and wall shear stress were studied. Moreover, based on the above results, the kinetic energy transfer phenomena in a real converter were investigated by applying the mathematical models.

A simplified model, in which the calculation region was reduced to save calculation compared to simulations of the whole region of the converter, was used in the mathematical simulation. In addition, this method was also used in the simulation of real converters. This approach makes it possible to simulate the Laval nozzle flow jet and the cavity separately when using different turbulence models.

In the top blown converter model, a comparison between the physical model and the mathematical model showed a good relative difference of 2.5% and 6.1% for the cavity depth and radius, respectively. In addition, the predicted mixing time showed a good relative difference of 2.8% in comparison to the experimental data. In an optimization of a combined top-bottom blown converter, a new bottom tuyere scheme with an asymmetrical configuration was found to be one of the best cases with respect to a decreased mixing time in the bath. An industrial investigation showed that the application effects of the new tuyere scheme yield a better stirring condition in the bath compared to the original case. Furthermore, the results indicated that the mixing time for a combined top-bottom-side blown converter was decreased profoundly compared to a conventional combined top-bottom blown converter. It was found that the side wall shear stress is increased by introducing side blowing, especially in the region near the side blowing plume.

For a 100 t converter in real, the fundamental aspects of kinetic energy transfer from a top and bottom gas to the bath were explored. The analyses revealed that the energy transfer is less efficient when the top lance height is lowered or the flowrate is increased in the top blowing operations. However, an inverse trend was found. Namely, that the kinetic energy transfer is increased when the bottom flowrate is increased in the current bottom blowing operations. In addition, the slag on top of the bath is found to dissipate 6.6%, 9.4% and 11.2% for the slag masses 5, 9 and 15 t compared to the case without slag on top of the surface of the bath, respectively. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xii, 47 p.
Keyword
BOF, physical model, mathematical model, mixing time, kinetic enregy
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-175462 (URN)978-91-7595-714-2 (ISBN)
Public defence
2015-11-06, M3, Brinellvägen 68, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20151015

Available from: 2015-10-15 Created: 2015-10-15 Last updated: 2015-10-15Bibliographically approved

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Zhou, Xiaobin

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