Shungo Natsui, Tohoku University, Japan

Co-Author:
Mizuki Tanaka, Tohoku University
Ryusho Honda, Tohoku University
Andrey Stephan Siahaan, Tohoku University
Hiroshi Nogami, Tohoku University

Abstract:
A numerical model of sintered iron ore deformation during ironmaking blast furnace processes helps to achieve superior process operations, particularly with the current goal of decarbonization. In this study, the high-temperature softening behavior of sintered iron ore characterized by a low-melting-point molten slag core and solid iron-rich phase shell structure was modeled using the Bingham plastic fluid model with an additional structural force that expresses the stiffness. The shape matching (SM) method was incorporated into the framework of the smoothed particle hydrodynamics (SPH) method, the stiffness parameter in the SM scheme was varied, and consistency with experimentally observed results was confirmed. The model was verified by comparing the simulated and experimentally determined 3D shape of sintered ore particles with different reduction rates after heating to various temperatures from 1473 to 1673 K. Furthermore, case studies simulating the softening and melting of the sintered ore particle bed in the cohesive zone were performed. We can expand this model's applicable range by experimental investigation of the effect of the composition of various types of ores on deformation behavior, and the mixing effect of various ores on bed deformation behavior could be clarified in detail.

Özgür Aslan, Erdemir Oyak Mining Metalluryg Turkey, Turkey

Co-Author:
Aytaç Altan, Zonguldak Bulent Ecevit University
Rıfat Hacıoğlu, Zonguldak Bulent Ecevit University

Abstract:
Pulverized coal injection (PCI) plants play significant role in reducing the blast furnace total energy consumption. Injecting desired amount of pulverized coal to a blast furnace is important not only for energy saving but also for process health. Pulverized coal injection rates from a PCI plant to a blast furnace is automatically controlled by logical algorithms and PID controllers of the automation system libraries. Since industrial plants do not have exact mathematical model, parameters of PID controller are determined according to the system dynamic response observed as a result of the experimental tests. Due to the system dynamics changes by time, the controller can not provide desired proves variable and parameters of PID controller need to be re-configured. Model reference adaptive controllers (MRAC) are used in many industrial applications in which the mathematical model of the system is unknown and the dynamic response of the system is changing over time. In this study, MIT and Lyapunov based model reference adaptive controller is applied in a pulverized coal injection tank pressure control system of a PCI facility, which is the critical process ironmaking energy consumption. In addition, fuzzy based adaptation gain regulation is proposed to improve MRAC performance. Adaptation speed and performance of MRAC is analyzed under disturbance effect. Control performance results of fuzzy based gain regulation MRAC is compared with PID controller and It is observed that MRAC shows better performance.

Bharath Rangavittal, KTH Royal Institute of Technology , Sweden

Co-Author:
Michael Vynnycky, University of Limerick
Björn Glaser, KTH Royal Institute of Technology

Abstract:
Development of mathematical models which include complex multiphase flow, coupled with heat exchange and chemical reactions, is necessary for understanding the inner state of the blast furnace. In this work, a novel approach using asymptotic methods is developed to model the transient gas-solid flow behaviour in the blast furnace. This is done by reducing the earlier developed Euler-Euler models with scaling assumptions that are based on the fact that the residence time of gas in the blast furnace is usually smaller than that of solid by several orders of magnitude. Results from this reduced model yield gas and solid flow patterns inside the blast furnace. In parallel, another model is developed by combining Discrete Element Method (DEM) and Computation Fluid Dynamics (CFD) to precisely simulate the gas flow and solid motion in the blast furnace. A qualitative comparative study between velocity patterns obtained from both the models is carried out. It is believed that asymptotic modelling could possibly open the doors to a computationally efficient approach for predicting the inner state of the blast furnace.

Alexander Schmitz, Paul Wurth S.A., Luxembourg

Co-Author:
Lijia Wu, AG der Dillinger Hüttenwerke
Juraj Micák, Paul Wurth S.A.
Cédric Schockaert, Paul Wurth S.A.
Rongshan Lin, AG der Dillinger Hüttenwerke
Dieter Senk, RWTH Aachen University
Alexander Babich, RWTH Aachen University
Jean-Paul Simoes, RWTH Aachen University

Abstract:
The ironmaking industry is nowadays facing the great challenge of process optimization and transformation regarding the current ecological and economic requirements. Since the blast furnace is still the main facility for metallic iron production, a stable blast furnace operation aiming at lowering reducing agent consumption remains the main target in the daily business. Thus, a well-controlled blast furnace thermal state should base on a reliable thermal state prediction. Compared to the silicon content in hot metal, the hot metal temperature is considered to be more representative of the current thermal state. Hence, for model fine-tuning, many thermal state prediction models especially data-driven models require not only high measurement accuracy of hot metal temperature measurement but also enough datasets. After the successful commissioning of the multi-wavelength pyrometer for continuous hot metal temperature measurement on ROGESA blast furnace NO. 5, a new machine learning model is developed and its performance is compared with the model that is based on traditional immersion lance measurement. This newly developed machine learning model will be integrated into the current running expert system (BFXpert) platform for developing a rule-based thermal control model

Jörg Adam, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Christoph Thaler, voestalpine AG
Ramona Eßbichl, voestalpine AG
Christian Rittenschober, voestalpine AG
Andrej Johnen, thyssenkrupp Steel Europe AG

Abstract:
The damage of a blast furnace tuyere is an unpredictable incident, happening in average between 30 and 100 times a year. As a result, two hours, in some cases up to eight hours shut down are necessary to change such cooling elements. Production loss, extra coke and steam for shut down increase the costs of hot metal (HM) production. Unplanned stoppages due to damages at the blast furnace tuyeres also cause additional emissions like CO2 etc. In the last decade BFI, in cooperation with various national and international partners, developed innovative systems for the observation of BF tuyere operation and the protection of BF tuyeres. The objectives were to generate advanced knowledge about tuyere damage mechanisms by the development of innovative systems for the monitoring of BF tuyeres during operation and to point out measures to extend BF tuyere operating life. The presentation will focus on:  BF measuring tuyeres with fibre optical temperature measurement  Optical monitoring system The presentation gives an overview about the investigations, findings and results of different national and international projects.

Hauke Bartusch, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Andreas Feiterna, AG der Dillinger Hüttenwerke
Dan Iulian Durneata, AG der Dillinger Hüttenwerke
Thorsten Hauck, VDEh-Betriebsforschungsinstitut GmbH
Yalcin Kaymak, VDEh-Betriebsforschungsinstitut GmbH

Abstract:
The wear of the blast furnace hearth lining defines its campaign life. Due to the excessive costs of the relining, this is one of the most important economic factors of blast furnace ironmaking. As current state of art, hearth wear cannot reliably be measured directly. It is deduced from the temperature measurements in the refractory wall. Increases in the maximum observed temperatures are interpreted as additional wear. Nevertheless, the analysis of hearth wall temperatures suggests that other operational factors such as thermal hearth state and liquid flow also affect those temperature readings. Due to the harsh environment inside the hearth, it is impossible to directly measure factors describing such hearth processes. Dillinger BF5 is equipped with deep thermocouples reaching more than 1.6m inside the refractory. Dillinger and BFI have developed data streaming techniques enabling analysis of data from such thermocouples with comparable high time resolution of a few seconds. In parallel, Dillinger has performed continuous temperature measurements of the tapped hot metal. Applying methods from data science like analysis of data clusters and search for correlations, repeating temperature fluctuation patterns have been found. These patterns were related to either the tapping regime or to hot blast stove changes. The comparison of the process data distributions with and without such patterns provided valuable information on the inner hearth processes and the health of the hearth lining. This enables better and more reliable monitoring of the blast furnace hearth state.

Paul Mark Geach, Primetals Technologies UK, United Kingdom

Abstract:
"Top fired stoves bring a number of operational advantages and therefore continue to increase in popularity. Various designs have been developed over recent years by a number of technology companies, with differing degrees of successful implementation. This results in an opportunity to identify the strong points of certain designs, and to have confidence in installation and operation with reference to particular designers. This paper will define the key features of a well-designed and constructed top fired stove, at the same time identifying the benefits (and problems) of different designs in terms of the stability of refractory construction, burner design, stove efficiency, environmental and CO2 emissions and operational longevity. The paper will identify why Primetals Technologies in collaboration with Yuxing Engineering & Technology propose particular designs of top fired stove, and why these designs can be trusted for implementation around the world. "

Akshay Bansal, ArcelorMittal, France

Co-Author:
Gérard Griffay, ArcelorMittal Global R&D
Dominique Sert, ArcelorMittal Global R&D
Antoine Moussalem, ArcelorMittal Global R&D
Elise Vouriot, ArcelorMittal Global R&D

Abstract:
Regenerative thermal exchangers are thermal devices capable of capturing & storing heat from a hot source and releasing the stored heat to a cold sink intermittently, repeating the cycles and therefore regenerating. In iron & steel industry, these exchangers are present in the form of hot blast stoves (hot air injected in blast-furnaces tuyeres) where the hot source is industrial gas combustion fumes, the cold blast constitutes the cold source and intermediate regenerator may typically be a checkerwork of refractory bricks or more recently a packed bed of refractory balls or pebbles. To support design and higher performance of pebble type regenerators, a numerical model of simplified combustion combined with heat transfer in a packed bed of pebbles is presented. Model results show a good order of magnitude of the bed temperature and its spatio-temporal gradient during both on-gas and on-blast cycles, in turn found to be aligned with experimental results in a laboratory scale pebble bed. The impact of the average pebble size on the heat transfer and therefore the global sizing of the regenerator is also discussed.

Ewout Tesselaar, Danieli Corus B.V, Netherlands

Co-Author:
Victor Van Straaten, Danieli Corus B.V

Abstract:
Before the introduction of dome combustion technology in the 1990s (ref. Kalugin first “shaftless” hot stove in operation in 1992), steel producers relied on either internal or external combustion chamber design hot blast stoves, with their advantages and disadvantages with respect to investment, process performance, reliability and maintenance requirement. Both these designs have reached a high level of maturity during nearly 150 years of use in the global steel industry. Over the past three decades, dome combustion technology was first embraced by the Russian steel industry and after the year 2000 by the Chinese steel industry. The design is currently considered the new industry standard for Greenfield Blast Furnace plants, in Asia in particular. Compared to the early design, later dome combustion hot blast stoves represent some steps forward, also driven by the implementation on a larger scale in the Chinese steel industry. This article analyses designs of early and later generations, also based on findings at systems that have been in operation for multiple years. The authors compare the designs with respect to mixing and combustion performance as well as condition and integrity of the refractories, presenting how the analyses and findings have resulted in the latest generation burner and refractory design features as implemented in three ongoing projects for steel producers in India.

Kosho Matsuda, Nippon Steel, Japan

Co-Author:
Ryuta Ishino, Nippon Steel Corporation
Seiya Teruya, Nippon Steel Corporation
Kenichi Higuchi, Nippon Steel Corporation
Kaoru Nakano, Nippon Steel Corporation
Hiroshi Mio, Nippon Steel Corporation

Abstract:
The reduction of carbon dioxide emission is one of the most important issues in the steel industry due to the large CO2 emitter. The steel is mainly produced by reducing iron ore using a blast furnace (BF), and its reducing agent is mostly carbon. Therefore, a low Reducing Agent Ratio (RAR) operation of the blast furnace is one of the solutions for reducing CO2 emissions. Kimitsu No.2 BF has been trying the low RAR operation by optimization of burden distribution, improvement of burden materials quality and so on. To further reduction of the RAR, the high-temperature blast operation is suggested to be an effective improvement. Because the high-temperature blast can raise an input amount of heat in the furnace, and it leads to the reduction of the RAR. Before operating under the high-temperature blast, there were two considerations; i.e. the one was the evaluation of the RAR reduction, and the other was the upgrading the hot blast stove. The reduction of RAR under the high-temperature blast operation was evaluated using a 2-dimensional mathematical model, and it was estimated that the RAR could be reduced below 490kg/t-p by 1300°C. The original hot blast stove had a limitation at 1200°C due to a heat resistance of the checker brick bracket. Thus, the material of the checker brick bracket was replaced with a high heat-resistant one. This new material made it possible to raise the blast temperature over 1300°C. The high-temperature operation was carried out in Kimitsu No.2 BF from 2019, and the RAR was able to be reduced to 492kg/t-p. This operating results were correlated well with the estimated value from the mathematical calculation.

Mikhail Kalugin , KALUGIN Top Combustion Solutions, Serbia

Co-Author:
Boris Prokofyev, KALUGIN JSC
Yury Murzin, KALUGIN JSC
Anton Subbotin, KALUGIN JSC
Sergey Ivlev, KALUGIN JSC

Abstract:
The global iron and steel industry is being impacted by a decline in steel demand and volatile situation in the global market of raw materials. Manufacturers are challenged to reduce the production cost of iron and steel by modernizing the existing production facilities in conditions of continuously growing requirements for provision of environmental measures. Iron and steel industry is considered as “dirty” production and many processes, including blast-furnace production, are sources of a big amount of combustion products and CO/NOx emissions. Many designs of hot stoves used for blast furnaces are not able to provide complete gas combustion during operation. On the contrary, top combustion stoves which have gained widespread use recently have proved its capability to remain environmentally “clean” during long-term operation. KALUGIN Company has developed and successfully implements top combustion hot blast stoves of its own design representing advanced and economically efficient technology meeting today’s high environmental requirements. Nowadays, modernization of existing stoves is being performed with different modernization options from replacement of existing burner design to full replacement of the stove. This paper gives a comprehensive assessment of various modernization options on the basis of such parameters as productivity, capital expenditures, project implementation period, reduction in CO and NOx emissions, which enables to choose the best option for modernization of existing facilities to improve productive efficiency and significantly reduce harmful emissions having adverse environmental impacts.

Hiroaki Sumikawa, NIPPON STEEL ENGINEERING CO., LTD., Japan

Co-Author:
Yu Kurakake, NIPPON STEEL ENGINEERING CO., LTD.
Takashi Fukuoka, NIPPON STEEL ENGINEERING CO., LTD.
Hironobu Ishikawa, NIPPON STEEL ENGINEERING CO., LTD.

Abstract:
One of the effective ways to decrease coke consumption and reduce CO2 emissions is to increase the blast temperature, but SCC caused by NOx and limited heat resistance capability of checker support lead to limits in dome temperature and waste gas temperature, respectively and therefore maximum blast temperature is, in general, 1200℃. NSE developed low NOx burner and new checker support so that the temperature at dome can be increased by 30℃ and waste gas by 100℃, allowing higher blast temperature. In addition, downsizing reduced initial cost of the new or modification of hot stove. We have delivered 5 units of this type of hot stove to large blast furnaces in Japan, and they are currently in stable operation. Furthermore in combination with our Waste gas Heat Recovery System（WHRS）for Hot Stove, further reduction CO2 emissions can be realized. Our WHRS is of heat medium circulation type, and has characteristics that enable to control the recovered heat and also provide the flexibility to install the heat receiving unit and heating unit separately, resulting in advantage of ①High efficiency of heat recovery, ②High layout flexibility ③Easy maintenance. In this paper, we describe the performance and recently orders of this equipment.

Floris van Laar, Allied Mineral Products, Canada

Co-Author:
Robert Byerman, Cleveland-Cliffs Burns Harbor Inc.
Robert Hansen, Hansen Refractory Consulting Services
Floris van Laar, Allied Mineral Technical Services

Abstract:
This paper will discuss novel repair methods for refractory systems in Hot Blast Stoves. The failure of refractory systems in a fast-paced industry creates demand for reliable repairs that offer the shortest timeline. Therefore, innovative solutions must improve the refractory design and installation methods to repair older, traditional refractory systems promptly. An alternative design with monolithic materials was successfully implemented in 2020 and 2021 at stove D1 and D3, and currently stove C4 at Cleveland Cliffs Burns Harbor. Failure of the traditional (brick) hot stove refractory system led to the casting of a complete monolithic dome and large sections of the walls. A post-construction analysis will demonstrate the validity and feasibility of the design.