Fuming Zhang, Shougang Group Co., Ltd., China

Abstract:
In recent years, after the commissioning of many blast furnaces, there are frequent problems such as hearth lining temperature raising, local overheating, abnormal erosion and so on, even many hearth lining breakout accidents occurred. Based on the production practice and investigation of blast furnace, this paper analyzes and researches the abnormal damage of hearth lining, obtains the main reasons and mechanisms of abnormal erosion, and proposes some effective technical measures and approaches to prolong the campaign life of hearth. The shape, position and liquid permeability of dead coke column have important influence on melting slag and hot metal discharge. The hot metal circular flow is the main cause of abnormal erosion of hearth lining. It is concluded that the blast furnace design must follow the theory of reasonable temperature distribution, control the reasonable distribution of temperature field in the bottom and hearth, attach importance to the optimization of hearth lining structure design, and construct the dissipative structure system of blast furnace with self-organized characteristics. In blast furnace operation, must pay attention to the stability of hearth operation, keep the hearth with good performances of gas permeability and liquid permeability, and control the shape, position and structure of hearth dead coke column. Strengthen the melting slag and hot metal management of hearth, especially control the process of tapping, restrain the hot metal circular flow along the edge of the hearth side wall, control the temperature distribution of hearth side wall and bottom, and restrain the abnormal erosion of hearth side wall lining. Promote the maintenance and rehabilitation of hearth lining function, add the titanium compound to protect hearth lining reasonably, strengthen hearth cooling management, reinforce the monitoring and control of hearth lining temperature, etc. The effective technical measures to prolong the campaign life of modern blast furnace are put forward.

Henrik Saxen, Abo Akademi University, Finland

Co-Author:
Jan van der Stel, Tata Steel Europe
Gerard Louwerse, Tata Steel Europe

Abstract:
The life length of the blast furnace is usually determined by the wear of the hearth refractory, so it is important to estimate the extent of the hearth wear during the campaign. Since it is impossible to directly measure the thickness of the remaining refractories, approaches based on inverse heat transfer formulations have been proposed. These one- or two-dimensional models of the system estimate how the position of the inner hearth profile progresses throughout the campaign by solving a sequence of static states based on temperatures measured by thermocouples in the lining. By this procedure it is also possible to track the formation of skull on the hot face. Crucial parts for the hearth wear are the regions close to the taphole, where the liquid flow is strongest. However, the thermal conditions in these regions make the use of one- or two-dimensional models incorrect since the taphole, when operated, acts as an additional heat source and further induces strong short-term dynamics that should not be neglected. The paper proposes an inverse heat transfer model that appropriately considers the heat source of the liquids in the taphole and the dynamics caused by the intermittent tapping operation. The model focuses on the region around the taphole and estimates the position of the hot face, i.e., the inner end of the “mushroom” formed by the taphole mud, based on the time evolution of the temperatures of the closest thermocouples in the lining. The paper describes the basic assumptions and equations of the model and presents an application of it to measurements from a large blast furnace. The estimates of the local wall-mushroom thicknesses on the different sides of the taphole are found to be correlated and also to follow the changes in the taphole length, which indicates the feasibility of the approach.

Filipe Sathler, ArcelorMittal Tubarão, Brazil

Co-Author:
Franklin Alexandre da Silva, ArcelorMittal Brazil
Renato Sarmento da Costa, ArcelorMittal Brazil
Filipe Sathler, ArcelorMittal Brazil
Leonardo Passos Perdigão, ArcelorMittal Brazil
Estefan Campos Ribeiro, ArcelorMittal Brazil
Claudio Cesar da Costa, ArcelorMittal Brazil
Frederico Godinho Cunha, ArcelorMittal Brazil

Abstract:
This work describes the history and improvements of the second campaign of ArcelorMittal Tubarão Blast Furnace #3 that began on July 2014. There was a blowdown in April 2020 due to crisis period but returned to operate in October 2020 (same campaign without hearth repair). With Inner Volume of 3617 m³, 4 tap holes, 12,5m of hearth diameter and 34 tuyeres, blast furnace process and equipment were improved in several steps. After blow in on 2014, high pulverized coal injection project has started, decreasing total coke rate from 350 kg/t in 2014 to below than 290 kg/t. During the coke rate evolution, many challenges were faced to sustain blast furnace stability, for example: hearth temperature control, raw material quality worsening, jumbo cooling damage, equipment availability, blowdown with salamander tapping and blow in with remaining salamander. To overcome those challenges, developments such as burden distribution improvements, burden segregation tests, process control, integrated management and raw materials quality adjustments. This paper presents highlights of main events and developments of blast furnace #3 second campaign.

Xue Feng Dong, School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Australia

Co-Author:
John Tsalapatis, Ironmaking, Liberty Primary Steel
Matthew Middleton, Ironmaking, Liberty Primary Steel
Paul Zulli, School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong

Abstract:
Liberty Primary Steel’s Whyalla No. 2 Blast Furnace (W2BF) has operated for over 17 years since blow-in in 2004. The measured refractory temperature trends in the hearth show unique variations at different stages during this campaign, influenced by a variety of different refractory and operational conditions. From an operational perspective, an investigation was begun to more deeply understand the hearth and refractory condition throughout the whole W2BF current campaign. This included detailed investigations of the refractory, coke bed status and corresponding liquid flow behaviour in the hearth. In this study, a methodology was proposed to help explain the refractory temperature measurements (trend) based on simplified and comprehensive fluid flow and heat transfer modelling, measured refractory temperatures and other relevant operational data. Results of this comprehensive study show that the estimations of hearth refractory and hearth conditions determined from different sources are consistent over the course of the campaign. The predictions are verified through comparison between calculated and measured data, over the whole campaign life.

Guanjun Chen, Research Institute of Technology in SHOUGANG Group, China

Abstract:
The energy consumption in iron-making process accounts for the main part of the total energy consumption in iron and steel industry, which is the focus of iron and steel energy conservation. Hot blast stove technology and blast temperature in China have greatly improved after more than ten years introduction, digestion and absorption, and independent innovation, but there has been a decline in recent years. According to the basic methods to improve blast temperature, the relationship between theoretical combustion temperature, preheating temperature and calorific value of gas is discussed. Through the comparison of domestic and foreign technologies such as blending high calorific value gas, preheating by heat exchanger, preheating by hot blast stove itself and preheating by high temperature air combustion, etc. It is clarified that high blast temperature of 1250 ~ 1300 ℃ has been achieved by adopting the double preheating technology of air and gas with high temperature preheating furnace on the hot blast stove of large blast furnace. In combination with the problems of cracking of furnace shell, deformation of corrugated compensator and corrosion of gas pipe network in the hot blast stove of JINGTANG No. 2 blast furnace(5500m3) in recent years, measures such as controlling the top temperature, surface temperature and displacement monitoring of expansion joints are taken to improve the blast temperature. Through comparison of main blast furnace indexes before and after raising the blast temperature in 2014 and 2016, it is shown that the blast temperature has picked up somewhat in recent years and the energy consumption level has decreased. The research on blast temperature uniformity shows that the method of stabilizing blast temperature can effectively improve the average blast temperature. The influence of parameters such as the temperature of combustion-supporting air before and after raising the blast temperature, the preheating temperature of gas, the calorific value, the flow rate, the dome, the blast temperature and the smoke exhaust temperature on raising the blast temperature were emphatically studied. At the same time, it is pointed out that there is a technical problem to realize high blast temperature for a long time and there is a long way to go.

Afshin Sadri, Hatch, Canada

Co-Author:
Wai Lai (Winnie) Ying, Hatch

Abstract:
For the most part, blast furnaces' campaign life relies on the condition of their hearth refractory lining. The hearth refractory lining mainly consists of carbon, micropores, graphite, and ceramic caps or some combination of two or three of these mentioned brick types. Blast furnace lining undergoes severe thermal-mechanical and thermal-chemical abuses that result in its wear and deterioration. Aside from direct hot metal wear, penetration and percolation of gasses within the lining, particularly the walls, affect the lining by causing chemical instability and failure of its material properties. In other words, the integrity of the blast furnace refractory systems is critical to its continuous operation. Hence, a comprehensive, multisource, risk-based, and dynamic management program is required to ensure that no sudden failures interrupt the operation. The hearth being the critical section of the furnace, its refractory thickness and quality must always be known. This information requires reliable and steady data sources acquired during furnace operation. The primary data is provided by various non-destructive testing (NDT) inspection and monitoring techniques, which do not interrupt furnace operation. The secondary data is provided by furnace operation and controls, such as the coke, pellet/sinter, flux quality and chemistry, all the output gases, chemistry, and temperatures. An integrated risk-based refractory management system is designed to reduce the probability of lining failure and increase the furnace campaign life.

Reinoud van Laar, Danieli Corus BV, Netherlands

Abstract:
-abstract

Martina Hanel, Mettop GmbH, Austria

Co-Author:
Hans-Jörg Krassnig, Mettop GmbH
Andreas Filzwieser, Mettop GmbH
Martina Hanel, Mettop GmbH

Abstract:
ILTEC is a new patented cooling technology, developed by Mettop GmbH in Austria, to overcome the disadvantages of water by using an alternative cooling medium, namely the ionic liquid IL-B2001. Since the use of water - today’s standard cooling medium - has major drawbacks as it can cause fatal explosions in case of leakages or malfunction. In contrast to that, IL-B2001 is non-flammable, non-corrosive, non-toxic and minimizes explosions due its low vapor pressure. Not only in highly stressed areas, as our reference at the blast furnace tap hole of ArcelorMittal Bremen shows, an alternative cooling medium minimizes the risks of fatal accidents. Also new ways of furnace cooling can be achieved in order to increase the lifetime of lances, side wall areas and even furnace bottom areas. The paper will highlight potential as well as already implemented applications for the iron and steel industry for making iron and steelmaking a more safe industry.

Martina Hanel, Mettop GmbH, Austria

Co-Author:
Javier Bolado, Welding Copper
Andreas Filzwieser, Mettop GmbH
Hans-Jörg Krassnig, Mettop GmbH

Abstract:
Mettop and WeCo have developed an innovative casting process enabling the only real copper-in-copper pipe cast by cooling with ionic liquid. The result is excellent metallurgical bond between copper tube and copper casting which leads to both long life time and recyclability of the copper cooler. Mettop and WeCo joined forces to develop this new safe production method for copper coolers aiming for improved thermal and mechanical properties and consequently extended lifetime not only limited to tuyeres. In order to get the best performance and the longest lifetime of these tuyeres it is best to use copper tubing for the cooling circuits. This entails the challenge of putting a thin metal structure into a surrounding with a large amount of liquid metal with a higher temperature then the melting point of the tube. Therefore a method we developed which allows sufficient refrigeration of a copper cooling circuit during the casting process in order to prevent the melting or deformation of the tube. As the cooling with gases is not sufficient and the use of water is extremely dangerous in presence of liquid metals - the only viable option keeping work safety in mind, is to cool with an Ionic Liquid. These liquids can be tailored in their characteristics in order to fit the application. In this case it is a cooling medium which can be used up to 250 °C and which is safe in handling and in case of direct contact to liquid metal. Mettop holds the patent to the only non-corrosive and non-toxic Ionic Liquid specifically designed for metallurgical applications – the IL-B2001. Therefore a co-operation between WeCo and Mettop has been formed in order to overcome the challenges of producing large cooling elements which are entirely made from copper in a safe way.

Edward Long, Primetals Technologies, United Kingdom

Co-Author:
Ross Edmond, Primetals Technologies
Jarmo Naula, SSAB Europe Oy

Abstract:
In a blast furnace, copper staves are often used to protect the shell in the highest heat zones. These staves are in turn protected from the abrasive burden material by freezing semi-molten material onto the stave face, forming a skull and preventing wear. The stability of this skull is therefore essential to achieving a long stave life which consequently allows a longer and more stable blast furnace campaign. Primetals Technologies have developed a solution which traps burden material at the front of the stave whilst still allowing liquids through to the copper face – the result is a more stable skull and improved overall process stability. This paper describes the equipment operated at SSAB Raahe since August 2019 and compares performance against the traditional design of stave. This paper describes the new stave design and its technical and commercial benefits over other designs, supported by operational data.

Eustáquio Vieira Junior, Ternium Brasil, Brazil

Abstract:
COMPARATIVE ANALYSIS OF BLAST FURNACE COOLER SYSTEM PERFORMANCE WITH DIFFERENT PRESERVATION TECHNIQUES AND DESIGN CONDITIONS Blast Furnace 2 of Ternium Brasil steelmaking company, in Rio de Janeiro, started to operate in December 16th, 2010. During its service life, the cast iron stave coolers displaced into the blast furnace and the copper stave coolers deformed, generating the lost of refrigeration capacity of these cooling system components. This paper presents the evaluation of techniques used to maintain the stability of the equipment shell, emphasizing the aspects of fluid dynamics, maintenance methods and the thermal consequences in stave cooler bodies. The main results of this research are the best procedures to stabilize the cooler system in good conditions without causing damages in the Blast Furnaces shell, and improvements in actual maintenance techniques to preserve the equipment and extend its service life. Keywords: Blast Furnace; Stave Cooler; Fluid Dynamics; Computational Fluid Dynamics.

Rodrigo M. de Carvalho, Universidade Federal do Rio de Janeiro, Brazil

Co-Author:
Luis Marcelo Marques Tavares, UFRJ
Emerson Reikdal da Cunha, UFRJ
Rodrigo Magalhaes de Carvalho, UFRJ
Bruno Pinheiro da Silva, Ternium

Abstract:
In the BLT systems, metallic and coke raw materials are discharging in layers into the blast furnace. The quantification of granular materials characteristics into the blast furnace, such as granulometric segregation and components distribution are difficult to perform. Therefore, this work consists in the development of a predictive model for the understanding and optimization of the blast furnace burden distribution equipped with a BLT (Bell less Top) based on calibrated high-fidelity DEM simulations, which were used as a viable and less expensive alternative compared to full scale experiments. To perform the simulations of the blast furnace charging, calibrations of contact parameters for coke and sinter were done, additionally the calibrations of pellets and lump ore parameters available in the literature. The present work contemplates the construction of a realistic virtual model of the blast furnace installed in Rio de Janeiro. Particles size distribution close to real materials were adopted in the simulations. The DEM simulations results allowed for the improvement of a phenomenological burden distribution model based on Park et al. (2011). The model was based on three charging strategies and four strategies for the discharge of the BLT hoppers and was able to predict and to determine the burden profile obtained in DEM simulations when compared to the original model by Park et al. (2011).

Dong-Geun Kim, Hyundai Steel Company, Korea, Republic of

Co-Author:
Hyuk Kim, Hyundai Steel Company
Ho Jun Youn, Hyundai Steel Company

Abstract:
The flow of slag through the coke bed largely influences the gas permeability in the dripping zone. The controlling parameters during the furnace operations are found to show a noticeable correlation with the conceptual slag holdup index. The relationship between the slag holdup index and plant data from the blast furnace (inner volume of 5250 m3) at the Hyundai Steel Company is analyzed. A practical range of the holdup index is derived based on three months of plant data. All the monitoring values in the furnace operation such as temperature, pressure from sensors, and the compositions/physical properties of the burden materials, etc. are used as-is. The mean size of the coke in the lower part of the furnace is predicted based on several times of coke sampling from the tuyeres. The voidage of the coke bed is derived from the measurement of the size distribution ratio of coke charges. A thermochemical software FactSage is used to calculate the slag viscosity. The guideline of operational parameters such as CaO/SiO2 basicity, wt%Al2O3 in burden materials, and the mean diameter of the coke charge are obtained in terms of the slag holdup index.

Claude Meisch, TMT, Luxembourg

Co-Author:
Richard Geyer, AG der Dillinger Hüttenwerke
Jürgen Hochhaus, AG der Dillinger Hüttenwerke
Volker Langer, TMT

Abstract:
An efficient blast furnace production process requires, amongst other things, a smooth cast house operation. The reliability of cast house equipment is also crucial for operational safety. It is therefore highly recommended to monitor the condition of the tapping equipment using the transmitters installed. A rudimentary equipment condition monitoring system is often part of the tapping equipment PLC software. However, when it comes to tapping process quality monitoring and predictive maintenance, PLC is not the right tool to get on. To fully exploit the potential of data-driven monitoring, TMT developed TapMan™, the tapping equipment condition monitoring and process control software that covers both operational and maintenance requirements. Automatic data analysis, based on both human experience and artificial intelligence, is a key feature of this tapping expert system. TapMan™ takes into account e.g. operator information on used consumables and main component replacement and indicates optimisation potential of the tapping process. This facilitates the benchmarking of tapping equipment and component lifetime amongst different furnaces. Operators can so benefit from each other’s experience, to reduce the operational costs and to optimise their spare parts management. Tapping process and equipment operation transparency is provided, including remote assistance if required. This Industry 4.0 application is continuously further developed by TMT and can be customised by clients according to their specific needs. TapMan™ is in operation at the Dillinger Blast Furnace 5 since 2020.

Henry Merten, Ruhr-Universität Bochum, Germany

Co-Author:
Siegmar Wirtz, Lehrstuhl für Energieanlagen und Energieprozesstechnik, Ruhr-Universität Bochum
Stephan Hojda, AG der Dillinger Hüttenwerke, Research & Development Iron and Coke Making
Rongshan Lin, AG der Dillinger Hüttenwerke, Research & Development Iron and Coke Making
Viktor Scherer, Lehrstuhl für Energieanlagen und Energieprozesstechnik, Ruhr-Universität Bochum

Abstract:
The lifetime of an industrial blast furnace is strongly affected by the campaign length of the hearth lining. Therefore, understanding the processes related to lining degradation in the hearth is essential. Since on-site measurements and experimental approaches can only provide a limited insight, numerical simulations are a valuable tool to evaluate the complex multiphase flow involved. The current work presents a numerical DEM-CFD simulation study of the multiphase processes in the blast furnace hearth. The movement of a particulate phase (coke particles), three continuous fluid phases (hot metal, liquid slag, gas) and their interactions are computed by a combined Eulerian-Lagrangian approach. In the BF hearth movement of the coke bed and the hot metal flow are intimately connected. Therefore, a coupled DEM-CFD approach is necessary to account for the transient movement of the coke particles instead of conventionally assuming a predefined porosity field. As the calculation of actual size particles in the total hearth is not feasible due to extensive computational cost, a static porosity field is assumed except for the region in front of the taphole. This results in two different domains for the CFD-side (total hearth) and the DEM-simulation (close-up of a coke bed section). Since steep velocity gradients and a high carbon dissolution rate prevail in this specific region, the movement of solid particles is of main interest. In particular, the principal flow direction of particles filling up the void space of dissolved coke is investigated. Since the path line of a single particle is determined by the interaction with the fluids (buoyancy and drag forces) and the mechanical interaction of solids, the numerical approach contributes a valuable insight into BF hearth phenomena, which are otherwise inaccessible.

Yale Zhang, Hatch, Canada

Co-Author:
Ronald Timmer, Algoma Steel Inc.
Aaron Tanninen, Algoma Steel Inc.
Ian Cameron, Hatch Ltd.
Yale Zhang, Hatch Ltd.
Luke Boivin, Hatch Ltd.

Abstract:
Management of the hearth drainage, and the related hot metal and slag liquid levels, is one of the most important requirements to maintain a smooth and productive blast furnace (BF) operation. Hatch implemented a Casting Guidance Model (CGM) in support of Algoma Steel’s efforts to enhance their casting practice. The CGM provides real-time information to help the operators as they adjust the furnace casting practices using richer information about the hearth status. The CGM provides two key benefits; (i) real-time monitoring, visualization, and forecasting of hot metal and slag levels; and (ii) scenario analysis to simulate the impact of casting practice changes in response to changing blast furnace conditions. This paper outlines the CGM functionality and the implementation strategy at Algoma BF7. Benefits to the casthouse operation and furnace performance are discussed.

Bart de Graaff, Danieli Corus, Netherlands

Abstract:
NOx emission from the Hot Blast System: Formation, effects, and the possibilities for its reduction Bart de Graaff, Jan de Weerdt, Yuriy Lytvynyuk (Danieli Corus) Keywords: Hot Blast Stoves, Hot Blast System, NOx formation, Emissions, Inter–crystalline Stress Corrosion INTRODUCTION The environmental footprint of the production of iron and steel is well–known by the industry and in general large improvements have been made in this field over the past decades [ref. 13]. However, in many places iron and steel companies are still a significant source of water and air pollution. With growing concerns from local societies over harmful emissions and the tightening of environmental regulations the need for mitigation remains high and important. One of the emissions that often gains attention of the ironmaking industry is the group of nitrous oxides, or NOx. This pollutant is formed within many of the present combustion processes, but one of its main sources and points of concern in the iron and steel industry is the Hot Blast System. Not only due its negative impact on the environment, but also because its influence on the occurrence of inter–crystalline stress corrosion. This article is intended to give an overview of the formation of NOx and the available methods to predict it, explaining the needs for its mitigation as well as providing certain directions to reduce its formation. CONSEQUENCES The reason why NOx is considered an undesired reaction product has two main reasons, first the environmental impacts. Secondly, and especially relevant for Hot Blast Systems, is the role NOx plays in the occurrence of Inter–Crystalline Stress Corrosion at the inside of the steel shell of the stoves. Environmental Impact The environmental effects of NOx have been a field of investigation for decades and are well documented [ref. 4]. One of the most important negative effects of NOx is the role it plays in

Filipe Sathler, ArcelorMittal Tubarão, Brazil

Co-Author:
Ramiro Da Conceição Do Nascimento Junior, IFES (Instituto Federal Do Espírito Do Santo)

Abstract:
With steel market development and steel production advance, there is a historical quality degradation of iron ores which are used for sinter production and for pig iron production at blast furnace. On the other hand, amid this scenario of mineral resources restrictions and raw materials worsening, blast furnace aims to achieve high productivity and high pulverized coal injection rates (PCR) in order to decrease operational costs. However, to sustain such results, it is necessary to ensure slag volume reduction on blast furnace lowering harmful elements input and to assure raw materials properties optimization (physical, chemical and metallurgical). Aligned with those perspectives, this work presents the discussion of industrial data obtained from an integrated steel plant in order to: evidence effects of granulometry and chemical quality of the iron ore mixture (sinter-feed) into the sintering process (permeability, density control, productivity, fuel consumption, burnt lime injection); correlate consequences of sinter chemical quality adjustments into sintering process; and, demonstrate the influence of sinter quality modifications (physical, chemical and metallurgical) into blast furnace operational performance (permeability, slag index, top gas efficiency, productivity, fuel consumption). Therefore, the improvements and discussions carried out throughout this work have allowed to mitigate effects of iron ore quality worsening into sintering process, sinter quality and blast furnace performance.

Michael Alter, ALTER Blast Furnace Consulting, United States

Co-Author:
Vladimir Naboka, PJSC “Zaporizhstal” Iron & Steel Works
Sergey Safonov , PJSC “Zaporizhstal” Iron & Steel Works
Sergey Karikov, PJSC “AZOVSTAL” Iron & Steel Works
Oleksii Chaika, Iron and Steel Institute of Z.I. Nekrasov National Academy of Sciences of Ukraine
Vitaliy Lebed, Iron and Steel Institute of Z.I. Nekrasov National Academy of Sciences of Ukraine
Bohdan Kornilov, Iron and Steel Institute named Z.I. Nekrasov National Academy of Sciences of Ukraine (ISI NASU);

Abstract:
The implementation of Pulverized Coal Injection (PCI) technology has reduced the lifetime of lining and cooling systems on Blast Furnaces in Ukraine. Efficient long-lasting operation with PCI required a new approach to furnace design and systems to control technical condition and thermal work of blast furnaces. Six blast furnaces of “MetInvest” have been upgraded to work with 160 kg/t PCI since 2014. These changes include: shaft cast-iron cooling plates replaced with copper; evaporative cooling system updated to modern cooling system having "cold" chemically purified water; profile design changed and furnaces equipped with Bell Less Top (BLT). In accordance with proposals of the Institute of Ferrous Metallurgy of National Academy of Science of Ukraine these blast furnaces were equipped with automated monitoring scheme of shaft-lining wear and in the hearth, thermal losses in the cooling system and also providing coke compensation calculations. One of the furnaces was equipped with the BLT charging model make available burden calculations and distribution. The mathematical models provide operators with critical information impacting the furnace operations on lining wear, skull formation, heat loads and losses on the shaft and hearth. This information is used for decision-making on optimization smelting regimes with PCI, which ensure the performance and efficiency while maintaining a lining and ensuring the safety of blast furnace operation. The automated system characterized the cooling system heat losses with 10 - 45 kg/t of coke required for compensation and established the dependency of blast furnace design and technical condition, loading parameters and operations technology. A reduction of specific coke rate of 2 – 20 kg/t was realized using the BLT charging model (varying by actual conditions.)

Yakov Gordon, Hatch, Canada

Co-Author:
Mikhail Polovets, Ural Federal University
Vladislav Panteleev, Ural Federal University
Konstantin Mironov, NTMK-Evraz
Segei Zagainov, Ural Federal University

Abstract:
Timely and complete taping of hot metal and slag is the main precondition of blast furnace intensive operation. Irregular taping leads to fluctuation of the level of liquid products in the furnace hearth, change in rate of material charging to the furnace and variations in a burden residence time in the furnace. Also it effects the thermal state of the furnace and chemical composition of the hot metal and slag. Ratio of tapped hot metal and slag is determined by physical properties of slag, diameter and length of hot metal taphole. Analysis of NTMK-Evraz blast furnaces operation showed significant fluctuations of this ratio. At average slag volume between 340-360 kg/thm the actual range of slag volume changes from 200 to 850 kg/thm. The fundamentals of mechanics of fluid and gases were applied to study the problem and laminate flow of hot metal and slag was assumed for the taphole. The ratio of the metal and slag mass in the taphole and hot metal and slag velocities were described as a function of slag parameters and taphole geometry. This approach allowed to derive numerical relationship between volumes of tapped hot metal and slag, slag viscosity and taphole design. Results of mathematical modeling were confirmed by actual performance parameters of NTMK-Evraz blast furnaces. It was found, that increase in slag to hot metal ratio led to the reduction in blast furnace productivity and reduction in vanadium partition to hot metal.

Edward Long, Primetals Technologies, United Kingdom

Co-Author:
Colin Morrison, Primetals Technologies
Jeremy Fletcher, Primetals Technologies
Mark Geach, Primetals Technologies

Abstract:
Consistently high hot blast temperature and the resultant lower fuel rate and CO2 emissions are important financial drivers for all blast furnace operators – Primetals Technologies’ solutions and development fully support these targets. As the steelmaking world tries to assess how to reduce CO2, and which future technologies to back, determining the benefits of spending capital on an existing blast furnace can be difficult. Spending capital on ancillary equipment such as the hot blast stove system can be a major part of this assessment. This paper will assess some of the technical solutions currently available as well as possible future technologies, particularly comparing the traditional internal combustion chamber and the top fired stoves solutions. The paper will assess CAPEX against OPEX reduction over various timescales, and the Return on Investment (ROI) possibilities.

Richard Willemsen, Danieli Corus, Netherlands

Co-Author:
Alain Woltheus, Danieli Corus
Magnus Sarbrant, Danieli Corus
Peter Öberg, SSAB Europe

Abstract:
As a part of the modernization of the Oxelösund Blast Furnace No. 4 hot blast system, SSAB and Danieli Corus built an additional hot blast stove in 2019, for commissioning in 2020. After careful preparation, the vessel shell was fully prefabricated in an off-site workshop and erected in its operating position in a single lift. This resulted in a much swifter and safer execution of both the on-site and off-site activities connected to the construction phase since the majority of the welding, coating and inspections could take place in the workshop - which is a working environment fully optimized for such activities - minimizing on-site work under plant regulations and more difficult circumstances. In addition to the construction method, the improved burner design is a key feature of this hot blast stove. With comprehensive benchmarking on main performance indicators against existing as well as alternative new designs, this burner type is an entirely new development. The final design was selected for its efficient mixing of combustion gas and air as well as its reduced emissions.

Fuming Zhang, Shougang Group Co., Ltd., China

Abstract:
Increasing the blast temperature can effectively reduce the fuel consumption of blast furnace (BF) and promote the BF stable and smooth production, which is one of the important developing directions of green and low carbon ironmaking technology. The heat transformation process and heat transfer characteristics of hot blast stove (HBS) are researched. The relationship between heating area and blast temperature of HBS is expounded through the study and analysis of heat transfer mechanism, and the view point of increasing heat flux to improve heat transfer in HBS is put forward. The relationships between theoretical combustion temperature, dome temperature and blast temperature of HBS are researched. The technical innovation and practice of high blast temperature are introduced by applying low heat value BF gas and recovering flue gas waste heat of HBS by coupling preheating and energy ladder-level utilization. High efficiency utilization and high value conversion of low heat value BF gas, increasing blast temperature, reducing fuel ratio and CO2 emission are the key-common technologies of BF ironmaking in the future.

Paul Geach, Primetals, United Kingdom

Co-Author:
Martin P Smith, Primetals Technologies Austria GmbH

Abstract:
The evolution of the Hot Blast Stove has been integral with the development of the blast furnace process for pig-iron production. As the steel industry adapts to deliver a reduced carbon footprint, the major technology changes in stoves and the operational improvement will be reviewed, with emphasis on the adoption of Top-Fired Stove technology. The paper will then assess different Top-Fired solutions, comparing the particular advantages and benefits of each, providing a critical summary of the available technologies.