Alexander Spatzker, thyssenkrupp Steel Europe AG, Germany

Co-Author:
Hai-Thong Ho, thyssenkrupp Steel Europe AG
Andrej Johnen, thyssenkrupp Steel Europe AG
Markus Wischermann, thyssenkrupp Steel Europe AG

Abstract:
In times of energy crisis, shortage of natural gas and geopolitical challenges the constant supply of electrical energy presents a great obstacle. During the last years, prices for electricity and natural gas were under constant fluctuations and even stable energy supply for households cannot be guaranteed anymore. Recently blackout plans were developed for the worst cases.In integrated steel works, the blast furnace (BF) and the coking plant contribute to the energy network. Beside hot metal and slag, the top gas of the BF is used as an energy source for various processes e.g. heating of hot stoves, coking plant or hot rolling mills. Surplus amounts of gas are used in the nearby power plants to produce electrical and thermal energy for district heating of surrounding households. For tk SE the produced electric energy covers more than the consumption of the entire plant and supplies the surplus to the electrical grid. This raises the question if this surplus can be further increased to save other fossil resources and help the electrical grid in times of power shortages. A project has been started to investigate possible operating conditions to increase either the amount of top gas or the calorific value of the BF top gas. This paper will show the theoretical and practical results of this project and discuss advantages and disadvantages of these parameters.

Michael Alter, ALTER Blast Furnace Consulting, United States

Co-Author:
Andrii Moskalyna, ISI NASU
Bohdan Kornilov, ISI NASU
Oleksii Chaika, ISI NASU

Abstract:
For the last 100 years, trends and classification of blast furnaces blow-in have been discussed. Development of blow-in subdivided into 3 periods: 1st - continued until end of 30s of XX century, characterized by lack of scientific knowledge, mysticism and based on previous experiences; 2nd - until the beginning of 70s, when "traditional" blow-in technology was mastered with one problem - difficulties with opening first casts and simultaneously overheating top; 3rd period is in progress nowadays, it includes developments of new methods for intensifying heat transfer during blow-in and scientifically generalize blow-in techniques. Major objectives of blow-in are to bring the blast furnace to normal operation, observing safety rules, in a short time, without significant costs, and to protect blast furnace and auxiliary equipment for long-term productive operation. These objectives are closely related to design features of blast furnaces, including the cooling system, type of lining, and furnace sizes, which have steadily increased from less than 500m3 to 5600m3. Complexity of understanding the processes of burden column heating during blow-in period that forms a gas flow and cohesive zone in it is the reason for numerous discussions about rational blow-in techniques: methods for calculating and placing burden layers in a blast furnace, usage of various additives to hot blast (nitrogen, natural gas, blast furnace or coke oven gases, oxygen, steam, etc.), the rate of hot blast volume increasing, its temperature ramp up and pressure drops trend along the burden column. In addition, a potential usage of wood in the blow-in burden, installation of narrowing rings into tuyeres or plug part of tuyere for blow-in are discussed. Recommendations for blast furnaces blow-ins and comparison of "Traditional" blow-in vs. "Progressive" and blow-in with nitrogen, developed by ISI NASU, is presented.

Reinoud van Laar, Danieli Corus B.V, Netherlands

Co-Author:
Peter Klut, Danieli Corus B.V
Victor Van Straaten, Danieli Corus B.V
Bart De Graaff, Danieli Corus B.V

Abstract:
Conversion of BF and BOF to DRP and EAF to reduce industrial CO2 emissions disguises the fact that BF technology is very efficient and economical and isn’t constrained by the availability and prices of scrap, DR-grade pellets, natural gas and hydrogen. It is therefore important to continue BF plant engineering and technological developments. This paper will address recent developments in our modern BF plant engineering and technology, which will be included in current projects in India. These include modern hydraulic top charging, dome combustion, dry gas cleaning system, alternative fuel and automation level II process control systems, but also allowances for future shaft injection to minimize CO2 emissions.

Sethu Ramalingam, Danieli Corus B.V, Netherlands

Co-Author:
Peter Klut, Danieli Corus B.V

Abstract:
Blast furnace top gas contains dust particles which are removed in two stages in order to use it further as fuel gas. Coarser dust particles are removed in the first step using gravity or cyclone dustcatchers and the finer particles are removed in the second step (dry bag filter). The temperature in the first step should be in the range of 115°C to allow optimum separation efficiency and avoid condensation of moisture. For the secondary cleaning, the temperature window is narrow that it shall neither damage the filter bags nor the gas loses its calorific value, requiring a conditioning tower in-between to cool the gas in case of surges of hot gas. The top gas is transported to the gas cleaning plant via various refractory pipes (offtakes, uptakes, downcomer and raw gas main). Hence the choice of the insulating refractory is critical for the smooth and optimal performance of the entire gas cleaning process. In this study the effect of GCP refractory is investigated through series of three-dimensional CFD models using commercial software Ansys Fluent. The physical refractories and the steel shells are included in the flow model enabling conjugate heat transfer (CHT) from the hot gas to the solid walls. As the flow field and boundary layers are predicted in better fashion the heat transfer coefficients are predicted near accurately in CFD. Performance of the refractory is studied through steady-state calculations but during blast furnace operations a peak in the gas temperature occurs for short period of time, which are analyzed through series of transient state calculations. The solid wall time scales are too low bottlenecking the computation time, which is tackled by several modelling techniques. Eventually the model is validated with an overheating (of the refractory) incident that occurred recently at a blast furnace.

Peter Klut, Danieli Corus B.V, Netherlands

Abstract:
Dry blast furnace gas cleaning technology offers great economic advantages when compared to traditional wet gas cleaning owing to its improved energy efficiency, lower cost, reduced plot space, and practically eliminated water consumption. Given the improved operational economics and – in some areas – the physical or economic scarcity of water, steel producers are shifting towards the application of blast furnace gas cleaning systems, in which the wet scrubber is replaced with a dry second gas treatment stage. The Danieli Corus solution is based upon proven technology that has been applied numerous times for cleaning aluminium smelter gases and anode baking fumes. The system consists of a gas conditioning tower, reagent injection system and (pressurized) filter modules with low pressure pulse cleaning. Currently, Danieli Corus is implementing this technology for three greenfield blast furnaces in India. This article presents the advantages of the proven technology as well as some improvements that will be applied during the ongoing projects. These improvements include steam reheat of (cold) blast furnace gas, single phase water injection in the conditioning tower and two stage countercurrent absorbent injection.

Ritesh Mishra, Jindal Steel & Power Angul Odisha, India

Co-Author:
Damodar Mittal, Jindal Steel & Power Angul Odisha India
Nadeem Khan, Jindal Steel & Power Angul Odisha India

Abstract:
Jindal Steel and Power, Angul commissioned its first blast furnace of 4554 m3 in May 2017 at Odisha, India. This Blast Furnace has achieved productivity of 3.16 t/m3 of working volume/day by producing more than 12000 tons of hot metal in a day. Productivity improvement of large blast furnace is achieved by improving permeability inside the cylindrical structure of furnace by changing Sinter chemistry based on alumina percentage as higher alumina deteriorate the physical properties of Sinter, reducing fines and moisture input in terms of kg/thm, Modifying burden mix blending in main charging conveyor. This approach helped to increase oxygen enrichment with coal injection in the furnace to increase productivity.

Andrey Stephan Siahaan, Tohoku University, Japan

Co-Author:
Shungo Natsu, Tohoku University
Hiroshi Nogami, Tohoku University

Abstract:
Burden-charged distribution in the top region of the iron-making blast furnace is an important issue, as the non-uniform distribution in this part may affect the gas flow, heat transfer, and chemical reaction inside. The rotary chute plays the role to deliver material from the hopper to the furnace top, and it comes in different sizes, which will eventually establish distinct particle movements while charging. In that regard, it is vital to understand the fundamentals of particle movement that determine burden distribution inside a blast furnace in corresponds to chute sizes. In this study, a three-dimensional model of the furnace-top and rotating chute was established to clarify the material movement and burden distribution of ore and coke (O/C), investigated at the particle scale using the discrete element method (DEM). Case studies of various chute sizes (length and diameter) were varied to analyze their influence on material flow behavior inside the chute during charging. The change of heap profile of O/C centralized or peripheralized layers during charging was analyzed on the effect of various chute sizes. In addition, the cross-section of ore and coke layers was examined, where the layer thickness and volume fractions on radial distance of each case were mapped and compared.

Pietro Cosentino, ArcelorMittal, France

Co-Author:
Sami-Alex Zaïmi, ArcelorMittal

Abstract:
Controlling the charging of the blast furnace is essential to ensure the burden distribution needed for a stable operation, high performance, low coke consumption and low CO2 emissions. The goal of this work is to study the impact of the chute geometry on the stream of particles. DEM has been chosen as the mathematical approach for simulating the granular flow. A series of simulations has been performed with modified geometries to study their impact on the stream of particles. To quantify that impact, the main aspects monitored were the thickness and the speed of the stream at the tip of the chute. The results showed the importance of simulating the proper geometry of the chute, as minor geometrical changes can have a big impact on the results. That approach brings perspectives on how to improve the geometry of the chute and on how it can influence the burden distribution in the furnace.

Jiook Park, POSCO, Korea, Republic of

Co-Author:
Dong-jo Lee, POSCO

Abstract:
To meet the unprecedented demand of environmental issues and tightened production cost, fuel consumption to produce iron and steel must be minimized to the limit. In blast furnace, maintaining circumferentially balanced state is critical for stable operation and minimizing fuel rate. Circumferentially unbalanced state of furnace will result irregular burden decent, thermal level instability and poor gas utilization and so on. Hence, furnace operators carefully monitor circumferential information of furnace and take several actions to keep furnace stable. Among several actions, burden profile control is one of the most effective actions to change inner state of furnace and achieve minimized fuel rate. Generally, optimum burden profile can be attained by rotating chute control (speed, angle, etc.) in bell-less type blast furnace. Unfortunately, in conventional control concept, only radial directional burden control is possible while there is barely no tool to control circumferential burden profile. In this study, circumferential burden stock level balancing system was developed for circumferential burden profile controlling and balancing. To decide when/where to control, furnace circumferential information such as top gas temperature, sounding level and tuyere combustion status were continuously monitored and key control parameters were derived from DEM burden decent simulation of bell-less top charging system. Once burden stock level of specific direction is too low or too high, top charging system was controlled to attain flattened stock level. Developed system was installed and tested at Pohang No.3 Blast furnace and it was found that standard deviation of 4 direction’s stock level can be effectively reduced by the system.

Eric Schaub, Paul Wurth Deutschland GmbH, Germany

Co-Author:
Markus Engelmann, Paul Wurth Deutschland GmbH
Volker Dulz, Paul Wurth Deutschland GmbH
Stephan Bamberg, Paul Wurth Deutschland GmbH
Markus Bierod, Paul Wurth Deutschland GmbH
Ralf Allmannsdörfer, Paul Wurth Deutschland GmbH

Abstract:
Title: BF Hearth Condition Monitoring and Hearth Repair / Re-profiling Authors: CUSTOMER – not yet confirmed, R. Allmannsdörfer, S. Bamberg, M. Bierod, V. Dulz, M. Engelmann, E. Schaub Key Words: Blast Furnace, Hearth, Wear Monitoring, Hearth Repair, Hearth Re-profiling Abstract: The operation of Blast Furnaces (BF) became even more challenging during the last years. Harsh conditions, like frequent stoppages and low production, poor raw material and a general uncertain outlook because of the need to reduce the carbon footprint make it difficult for operators to operate their BFs and to plan for the future. In this context it’s quite important for operators to have proper information and feedback regarding the condition of their BF hearth refractory and the consequences of the operation on the BF hearth, but also with regard to the uncertain future to, to extend the service life as much as possible. Repairs, if required, are often reduced to a minimum and “smart” repair procedures are requested. So called Multi-Point-Temperature-Sensor-Probes (MTP) help to monitor the condition of a BF hearth and sometimes help to extend the service life. They give precise feedback regarding the condition of the BF hearth, also with regard to the operation of the BF. Defects in the BF hearth refractory can be detected by these MTPs. Re-profiling repairs allows to extend the service life of a BF, typically by several years, as long as accompanied by proper condition monitoring. The following paper will illustrate the working principle of MTPs, will show typical applications and found refractory defects and will also provide an overview about possible and executed repairs on BF hearths.

Floris van Laar, Allied Mineral Products, Canada

Co-Author:
Floris van Laar, Allied Mineral Technical Services
Maria Grguric, Allied Mineral Technical Services
Richard Chaykowski, Allied Mineral Technical Services

Abstract:
This paper will discuss campaign extension strategies using partial repairs to refractory systems in blast furnace hearths. As the industry continues to rely on fewer blast furnaces to maximize iron output, the need for campaign extension strategies that minimizes down time becomes vital. Furthermore, complete hearth relines can prove to be lengthy, with large costs associated to manpower, materials, equipment, reduced production, and impact on steel cost. Hearth diagnostic and monitoring assessments can help identify the areas of concern and plan the best activities to meet or exceed existing campaign targets, while keeping the total cost in check.

Radha Raman Abhyuday, Tata Steel Ltd , India

Co-Author:
Sambit Joshi, Tata Steel Ltd
Padmapal ., Tata Steel Ltd
Shivendra Kumar Dubey, Tata Steel Ltd
Subhashis Kundu, Tata Steel Ltd
Shambhu Nath, Tata Steel Ltd

Abstract:
‘D’ Blast Furnace installed in 1923, was a 400 tpd furnace. It was upgraded to 800 tpd in 1967. In 1998 up gradation, furnace was the second at Tata Steel and sixteenth in India to have carbon hearth. The furnace has produced 6.96 million tonnes in its current campaign. The furnace has been subjected to frequent on and off mode of Operation, primarily due to fluctuations in the demand since 2008. After 15 years of successful operation, the furnace started showing signs of ageing, especially in the lower stack, Bosh/Belly and Tuyere jacket area. The furnace was plague with the problem of hot spots in the above-mentioned area. This led to catastrophic failures of cooling plates, flame shooting around the mantle ring, necessitating frequent blanking of tuyeres, grouting shutdowns and a centrally biased burden distribution. The above problem was taxing both the fuel rate and productivity of the furnace and therefore a repair plan to prolong the campaign life of the furnace was necessary. The 3rd term repair of 'D' furnace was a unique repair in the history of Tata Steel as it was the second attempt to have a multi campaign on the same hearth. The Blast Furnace team was not having any past experience of blowing down the furnace with its own team till tuyere level and capping the red-hot coke below tuyere level to make the furnace gas free for carrying out the repair jobs inside the furnace. The repair plan consisted of blowing down the furnace to the tuyere level, manual coke raking after nitrogen quenching, removal and leveling of coke, capping of hearth and repairing throat, tuyere jacket, Bosh, belly area without disturbing the bricks in stack area and carbon hearth. Key Words - Blast Furnace, Blow down, Stack, Burden, and campaign life.

Andre Fiedler, thyssenkrupp Steel Europe AG, Germany

Co-Author:
Jan Vogt, Refratechnik Steel GmbH
Tim Kruell, Dominion Deutschland GmbH

Abstract:
Due to premature wear accompanied by hot spots on the shell in the bosh and belly area of Blastfurnace 2 in Schwelgern a shotcrete repair by roboter became necessary. With a hearth diameter 14.9m and a production of up 12.000t/d Schwelgern BF2 is the largest BF in Europe. For the bosh and belly area that means a diameter of approx. 20m and a depth of 25m. This was the first time for this kind of repair in this area of a BF at Schwelgern. This work shall give an overview of the planning and the execution of the work on site done by thyssenkrupp Steel Europe AG, Refratechnik Steel GmbH and Dominion Deutschland GmbH. Which means on the one hand the planning of the blow-down process with the aim of not having to remove burden via tuyere area. The activities done in the casthouse if this should have been necessary and an overview of the success of the blow-down procedure Additionally it will be given an overview of why the applied refractory, Refrajetcrete with Hybrid technology from Refratechnik Steel GmbH, was chosen. The third point will focus on the used shotcrete roboter from the compamny of Dominion Deutschland GmbH. With the focus on why it was choosen and what changes had to be applied on the roboter to grant success on site for the use in the bosh and belly area.

Günther Schnell, Friedrich Kocks Gmbh & Co KG, Germany

Abstract:
While most of the Kocks 3-roll blocks are popular as finishing blocks in long product rolling mills, there are also applications, where a Kocks block can suit as alternative to a roughing as well as an intermediate mill. The smooth and gentle reduction behavior of the 3-roll pass, the most flexible stand change system in combination with a very compact and modular design allows an implementation in a very tight space. Especially in existing rolling mills space is very limited. Still being able to add additional reduction capacities grant some very crucial advantages. Bigger billet sizes can be used, or a different, more flexible distribution of the reduction in the stands is feasible. Which in consequence is a key factor in order to optimize the quality of the finished product. As a result, the productivity of the plant can be increased, and the rolling process can be optimized. New, more difficult to roll material grades, can be added to the product portfolio. All of this without major changes of the layout of the rolling mill. This paper describes the application and the unique advantages of the Kocks 3-roll technology, when used in a roughing but also in an intermediate mill.

Elmar Krieg, SMS group, Germany

Co-Author:
Wolfgang Scheffel, SMS group

Abstract:
Over the recent years, Jumbo Beam and Section Mills were newly built, modernized and successfully commissioned or are under construction. Such heavy rolling mills require special technologies and equipment like thermo-mechanical rolling as well as in-line water quenching. Furthermore, rolling of beams up to more than a ton per meter poses special requirements on the rolling mill equipment design and layout. In particular, solutions for covering a very wide range of product program will be introduced. Beside the introduction of the mill equipment and its technologies, the paper will focus on the today’s and tomorrow’s possibilities to provide digital solutions for process and quality optimization, data and energy management, lifecycle and predictive maintenance strategies. We will demonstrate how AI can be utilized to achieve prescriptive maintenance with significant operational cost improvements.

Faisal Alghamdi, SABIC, Saudi Arabia

Abstract:
Medium carbon steels are mostly used for spring and nail manufacturing applications. In this paper, the drawability and cold headability performance of wire rods, AISI 1040 and AISI 1045, produced using pollard-type nitrogen shroud casting were investigated. The material has been characterized “as hot-rolled” using several analytical methods: Decarburized depth/Core segregation, optical microscopy, and Nonmetallic Inclusion rating analysis. Both grades of AISI 1040 and 1045 were then deep drawn to wire to size 2.87 and 1.3 mm, respectively. Produced medium carbon steel wire rod had high ductility and excellent drawability with limitation in cold headability.

Antti Kaijalainen, University of Oulu, Finland

Abstract:
Formed steel sections are widely used in construction applications due to their relatively high strength and stiffness properties. Especially, cold-formed welded hollow sections provide cost-efficient and environmentally friendly alternatives compared to hot-formed sections. Cold deformation causes work-hardening of the material, which resulting in enhanced strength, although a corresponding loss of elongation and toughness. The aim of this work is to compare mechanical properties of i) as produced, ii) artificial aged (250 °C for 1 h) and iii) naturally 5-years aged cold formed S700 rectangular hollow section. The investigated hot rolled steel strip was produced thermomechanical rolling followed by direct quenching. The dimension of the investigated hollow section was 120x120x10 mm and the corner radii and the other tolerances compliant with EN 10219. Tensile properties and Charpy-V impact toughness were determined for the flat and corner area of the hollow section. The results showed that the tensile strength in the corner was slightly higher in comparison with the flat side, revealing higher cold deformation rate in the corner. Artificial ageing increased the strength level relatively higher than cold forming without losing any elongation properties. The impact energies were at the high level at -40 °C and -60 °C in cold formed and aged materials. Even at -80 °C, the CV results were 118 J/cm2. It is also notable that no difference in CV values between the flat and the corner samples were observed. Thus, the results showed that the flat side specimens testing provides sufficient information of mechanical properties of the cold formed rectangular hollow sections and no need demanding corner sample testing when the structural hollow section is produced by using the thermomechanical controlled and direct-quenched base material. Furthermore, results showed that cold formed S700 is excellent for offshore steels, as steels are used even colder conditions as before.

Eric Huelson, OnPoint Digital, Inc., United States

Co-Author:
Jonathon Richards, Tata Steel Ltd
Guillaume Tiffon, OnPoint Digital Solutions, LLC

Abstract:
Combustion control in a reheat furnace is an often-overlooked opportunity for fuel savings and steel quality improvements. With recent increases in natural gas and energy costs, fuel efficiency is more important than ever for maintaining viable steel production. Despite this many of today’s reheat firing schemes are based on rudimentary mass flow indicators and minimal control logic resulting in high levels of excess O2 (4%-8%) and significant extra fuel consumption worth hundreds of thousands of dollars annually. A simple solution is presented for zone-based combustion monitoring using a TDLAS laser monitoring system in a reheat furnace. The system has been used to spot failings caused by poor burner calibrations and targeted firebox corrections at a large steel mill. Moving forward control logic updates are planned to help improve furnace efficiencies and reduce fuel consumption. Furnace corrections and proposed efficiency solutions will be reviewed to illustrate the optimization journey and combustion improvement opportunities.

Elisa Salamone, Danieli Centro Combustion, Italy

Co-Author:
Alessandro Venanzini, Danieli Centro Combustion

Abstract:
The United Nations Climate change conference emphasized the commitment needed from the world to mitigate climate change, requiring a strong reduction in greenhouse gases emissions by 2030. The European Union allocated funds for innovative systems to reduce carbon dioxide emissions. On the path towards decarbonization, Danieli Centro Combustion finalized a study for an innovative furnace called “DRY PLUS FURNACE” (DPF), to counteract industrial furnaces being one of the largest sources of carbon emissions. The DPF is a Walking-Beam Furnace (WBF), based on the absence of cooling water inside the furnace, as losses through water-cooled components are the second major source of losses in traditional furnaces, with the goal of reducing carbon dioxide emissions in the steel industry. Danieli Centro Combustion took up the challenge to contribute in addressing climate change with this new furnace, whose main features and advantages are not just limited to carbon emission reduction, but also specific consumption improvements, absence of a water-treatment plant, increased billet heating quality, reduction of maintenance time, reduction of operating costs and savings in installation times. The billets inside the DPF are transported by means of dry walking beams. To reduce the height below the pass line and to simplify the under-furnace mechanism, a single frame is provided. The lifting and the travelling movements are performed through an electromechanical device driven by hydraulic cylinders. Frontal burners are installed in all top zones, while angle burners are installed in the bottom zones. This technology provides the flexibility to adopt any configuration to meet the customer’s needs with a low environmental impact and operating costs. Specifically, the benefits of the DPF compared to a traditional WBF are quantified as follows: - 10–35% specific consumption and CO2 reduction; - 20–40% operating costs reduction; - 90% ordinary maintenance cost reduction; - no water consumption; - no skid marks.

Toshihito Shimotani, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Japan

Co-Author:
Takuya Hihara, Toshiba Mitsubishi-Electric Industrial Systems Corporation
Hiroyuki Imanari, Toshiba Mitsubishi-Electric Industrial Systems Corporation
Masayasu Sekimoto, Toshiba Mitsubishi-Electric Industrial Systems Corporation
Takahiro Mitsui, Toshiba Mitsubishi-Electric Industrial Systems Corporation

Abstract:
Induction heaters are installed in many hot strip mills (HSM’s) to improve process control performance. Induction Heating (IH) is a non-contact heating method that uses electricity as an energy source and heats up the strip by the principle of electromagnetic induction. Therefore, depending on the source of the electricity, IH emits less carbon dioxide and has relatively higher heating efficiency than other heating methods, and so assists in achieving carbon neutrality. IH heating characteristics differ depending on the heating-coil and iron core shape of the primary conductor. Heating characteristics also differ depending on the through direction of the magnetic flux to the work pieces. In order to improve process control performance in a HSM, the optimum heating pattern should be determined depending on the above heating characteristics so that strip temperature can be appropriately controlled. In this paper, we introduce recent technology of analysis and control for IH , using the three types of IH provided by TMEIC as examples. First, as an example of computational simulation of IH, an overview of the three-dimensional finite element method (FEM) for magnetic field is introduced. By utilizing FEM, we can evaluate the heating characteristics of IH in various cases without needing experiments on actual equipment. Next, recent temperature control in a HSM using IH is introduced. During rolling, the required heat-up amount is dynamically calculated based on a numerical model of IH-heating and a temperature model based on the two-dimensional finite difference method. Furthermore, a calculation method for the optimum heat up pattern along the width direction is introduced. This method is based on the evolutionary computation algorithm. Optimal parameters for IH setup, such as position in width direction and power of IH, can be calculated even if several IHs of different types are combined.