Bernd Wemhöner, thyssenkrupp Steel Europe AG, Germany

Abstract:
The presentation describes the structure of the process control system of the Schwelgern coking plant, starting with the initial planning, the implementation and the continuous further development during ongoing operation. The complete system, starting from the field level, which is exclusively connected to the control systems via bus systems, to the extensive visualisation of the complex processes and the database system for long-term data storage, will be explained.

Anna-Katharina Hofecker, thyssenkrupp Steel Europe AG, Germany

Abstract:
The identification of weaknesses and the analyse of production losses is crucial to ensure the stable output and the proper production planning of a coke plant. This is, compared to other steel production plants, faced by two main challenges that make the analysis complex: It never completely stops production and the redundancies of all important production components multiply information input. Coke plant Schwelgern started to implement a Digital Failure Reporting and Analyzing System to address this complexity.

Fabian Rupp, Danieli Corus B.V, Germany

Co-Author:
Miguel Furlaneto, Danieli Corus B.V

Abstract:
Whereas originally, coke plant lifetime would be determined by its technical integrity and in more recent decades by its environmental compliance, steel producers who are developing their decarbonization strategies currently face the necessity to have both these aspects match the projected termination of coke consumption at their site. Coke plant technology has been developed to such a level of maturity that lifetime extension at minimum emissions to the environment is feasible under any scenario. However, with the potentially limited lifetime requirement dictated by the selected decarbonization scenario, applying modern technology may easily stretch the plant’s lifetime beyond requirement while requiring excess capex allocation. A coke plant comprises a large multitude of refractory constructions as well as mechanical equipment, all of which are connected to the plant’s lifetime capability, process performance and environmental performance. Based on comprehensive knowledge of coke plant technology as well as decades of experience in the design, construction and maintenance of coke plants, Giprokoks and Danieli Corus have developed condition assessment and lifetime extension strategies that allow for extending a plant’s lifetime to match plant lifecycle requirements while minimizing direct cost and production loss. These strategies may include minor or major repairs of and modifications to refractories as well as repairs of and modernization of mechanical equipment such as doors, valves, hoods and mains/ducting. In any scenario, a program for minimizing emissions to the environment and to comply with regulations will be advised.

Murat Yaman, Ereğli Iron and Steel Works, Co., Turkey

Co-Author:
Bülent Öztürk, Ereğli Demir ve Çelik Fabrikaları
Viorel Patriche, Fosbel GmbH
Tuna Keskinel, Ereğli Demir Çelik Fabrikaları
Christophe Leborgne, Fosbel GmbH

Abstract:
Oven walls in coke batteries that are in production for a long time can be damaged due to various reasons. To ensure production continuity, it is important to select a low-cost, short-time requiring, and effective method. Gunning, ceramic welding, and hot repair methods are the methods that can be selected in the repair process. Methods such as ceramic welding and gunning can be selected as a solution to light damages, but the repair of deepest damages reaching to middle section of the oven can be done by the hot repair method. Between battery wall repair methods, the most effective solution is the process of removing the bricks and knitting from it which is called hot repair. In this article, the methods that can be selected in the repair process of the oven refractory structure in batteries that have been manufactured for more than fifty years have been reviewed. It has been described that the repair of light and severe damages occurring to these batteries is possible in a short time with the recently developed material (Fused Silica Gunning Material). With this material, the life of the ovens was extended to 6 months by casting (gunning) to the depths of four and six combustion chambers in heavily damaged ovens requiring hot repair, which is deepest repair in the world. In these ovens production is continued thanks to this application. The existing refractory structure of ERDEMIR coke batteries, which continued to be in production since 1964 and which is one of the oldest batteries in the world, and the formation process of the structural damages have been demonstrated.

Gabriel Korkmaz, Paul Wurth S.A., Luxembourg

Co-Author:
Mathias Hoffmann, Paul Wurth S.A.
Wolfgang Kern, Paul Wurth Italia S.p.A.

Abstract:
Decarbonization route for most steelmakers is already described for the next decades. However, the remaining operation time of the existing coke oven plants will be a challenging task for the coke producers. The more and more stringent requirements of local and national authorities force the coke producers to continuously update the operation and equipment. In light of this situation various technologies have been developed to support the coke producers in order to meet the environmental requirements. Environment and safety aspects are to be respected and therefore it is necessary to keep attention on typical areas of coke oven plants to ensure a continuous and safe plant operation. Several new technologies have been developed over the last years and proven to be very effective in order to fulfil the requirements with regards to environmental protection. This paper will highlight the areas of concern in the different sections of a coke oven plant: from the coke oven battery, moving machines and by-product plant. Moreover, it will demonstrate effective solutions as upgrades or adjustments implemented in various coke oven plants all over the world to ensure the environmental protection performance. These technologies can be applied for new coke oven plants and for modernization of existing coke oven plants.

Sebastian Riethof, thyssenkrupp Steel Europe AG, Germany

Abstract:
The Climate change, which is becoming increasingly evident, has an impact on our plants worldwide. Temperature-sensitive processes in particular are significantly impaired by the longer periods of hot weather. Higher cooling capacity is becoming unavoidable for constant production. The raw coke oven gas (COG), generated at Coke Plant Schwelgern, is treated in the by-product plant and its valuable by-products are recovered by multi-stage absorbers. These processes are temperature-sensitive. The governmental permit limits the environment relevant concentration of substances like hydrogen sulphur in the purified COG and controls the limits via online monitoring. The efficiency of COG-treatment is sufficient, if the process is operated following the design parameters. The efficiency decreases during hot summer times which becomes more and more relevant. The original design of Coke Plant Schwelgern was not able to guarantee full production at hot summer times without violation of the environmental COG-limits. The necessary cooling capacity for the absorption processes at the Schwelgern coke plant is provided by cooling towers. Thus, the cooling capacity depends on the ambient conditions, the installation of additional chiller cooling capacity becomes necessary. Conventional chillers have a very high electrical energy requirement and, in addition, the coolant is harmful to the environment, alternative energy sources must be tapped. At Coke Plant Schwelgern, the by-product plant generates a steady flow of hot waste water, which is an untapped potential for chiller water generation. The so-called absorption chillers can use this heat source to generate cooling water for cooling down COG and circulating water feeds to optimize the COG-treatment during hot periods, guaranteeing full coke production without violation of environmental COG-limits. This presentation illustrates the theoretical considerations for this project, reflects about commissioning and presents first results.

Wolfgang Kern, Paul Wurth Italia S.p.A., Italy

Co-Author:
Alessio Ferraris, Paul Wurth Italia S.p.A.
Fabio Cerutti, Paul Wurth Italia S.p.A.
Gabriel Korkmaz, Paul Wurth S.A.

Abstract:
For many countries, steel production will rely for the foreseeable future, on the blast furnace route. There will be optimization processes taking place at the blast furnace, from PCI injection, coke rate reduction to Syngas injection to limit the carbon footprint. Nevertheless, availability of good quality coke at a reasonable price level will be required to ensure a stable operation of the Blast furnace in some regions for years to come. To produce good quality coke it is required to utilize high quality coking coals with excellent coking behavior to ensure a continuous and stable carbonization process through traditional top charged coke oven batteries. Due to the limited availability of good coking coals on the world market and the ever increasing cost for these coals, a trend can be seen with more and more coke producers changing from top charged coke oven battery operation to stamp charged coke oven battery operation in several parts of the world. When applying the stamp charging coke making process the selected coal blend will be compacted before charging into the coke oven. Such compacting will allow the coke producers to apply coals with less favorable carbonization behavior and still enable them to produce the desired high quality coke for the blast furnace operation at a lower cost. The stamp charging technology is particularly interesting in countries with large coal reserves, however the coals having lower or limited coking and carbonization characteristics. Through the introduction of the stamp charging process, these countries will be less dependent on the import of expensive coking coals. The paper will provide an overview on the coke making trends in several regions of the world.

Thomas Taylor, thyssenkrupp Steel Europe AG, Germany

Abstract:
This presentation contains the key data of coking plant Schwelgern including coke demand of Thyssenkrupp steel Europe at different stages. Short overview of the different D.R.I.-processes, chosen location in the “past” and “future”. Gas supply D.R.I taking both increasing gas prices and decreasing availability in Europe into account. The presentation will also give a closer look to the coking plant Schwelgern as bridging technology providing coke oven gas to D.R.I-processes and the effect on Thyssenkrupp Steel Europe as the result of reduced COG supply to other processes in the steel plant.

Peter Liszio, thyssenkrupp Steel Europe AG, Germany

Abstract:
Coking plant Schwelgern set the state of the art of cokemaking after commissioning in March 2003. This presentation is reflecting over the last 20 years and gives a resume about its pro and cons of design, production, environmental and management developments, raw material optimization and a future outlook.

Asuto Masuyama, NIPPON STEEL ENGINEERING CO., LTD., Japan

Abstract:
As the environmental problems become more serious in recent years, Iron and Steel Industry has been making various efforts to save energy and reduce CO2 emissions, especially in order to achieve carbon neutrality. Under such circumstances, coke dry quenching (hereinafter referred to as the “CDQ”) are attracting attention due to the following advantages. ・Power generation utilizing sensible heat of hot coke ・Improvement of Blast Furnace productivity leading to lower CO2 emissions Recently, NIPPON STEEL ENGINEERING CO., LTD. improved power generation by approximately 7% compared to conventional CDQ. In addition, our CDQ automatic control system, integrated with coke oven operation, enhances CDQ benefits and reduces running cost. This paper describes our latest CDQ technologies, including new power generation cycle and automation technology.

Michael Cremer, thyssenkrupp Steel Europe AG, Germany

Abstract:
Coke plant Schwelgern, commissioned in March 2003, is still running the biggest coke ovens worldwide with a coke output of more than 56 tons per oven. The so-called Coke Stabilizing Quenching, the state of the art regarding wet quenching processes, realizes the procedure of coke quenching. The two quenching towers are the highest industrial wood constructions worldwide and are hardly stressed by the coke quenching process itself. After more than 20 years and more than 50 million tons of produced coke, the quenching towers have reached the end of their life cycle. This presentation shows the dismantling and assembly of the southern quenching tower during ongoing coke plant operation.

Ömer Ece, İskenderun Iron and Steel Co., Turkey

Co-Author:
Erman Kaya, İskenderun Iron and Steel Co.

Abstract:
The main task of coke factories in Iskenderun Iron and Steel Co. (ISDEMIR) is to produce metallurgical coke needed by blast furnaces. The final stage of coke production is completed with the quenching processes. In ISDEMIR, it is used two types of methods which are dry and wet quenching in the coke plant. In this research, it is shown how the same coke battery oven, same blend and the same conditions effects the coke quality parameters, such as moisture, coke reactivity index, coke strength after reaction and blast furnace production process by wet and dry quenching methods.

Behnaz Rahmatmand, University of Newcastle, Australia

Co-Author:
Nicholas Ong, University of Newcastle
Kim Hockings, BHP Group
Salman Khoshk Rish, University of Newcastle

Abstract:
The reduction of CO2 emissions from blast furnace operations has received much attention in recent years. The introduction of hydrogen into the furnace is considered a promising solution for reducing the carbon intensity of blast furnace ironmaking. Although the substitution of pulverized coal and coke with hydrogen reduces the overall fuel rate, this can alter the thermal and chemical state inside the furnace, which in turn influences the reaction rate and the degradation mechanism of coke. This study investigates the impact of hydrogen injection and coke quality on coke gasification reactivity and kinetics. A high temperature thermogravimetric analyzer was used to study the CO2 and H2O gasification behaviour of coke lumps with CSR of 43.11 and 68.32 in the temperature range of 900-1200 °C. Three kinetic models, i.e., volumetric, random pore, and shrinking core, were used to explain the gasification behaviour. The shrinking core model was found to better fit the experimental data and was thus applied to calculate the gasification rate and to determine the reaction controlling mechanism. Coke reaction rates with H2O were up to 8 and 5 times greater than CO2 for low and high CSR cokes, respectively. Coke reactivity with H2O in the entire temperature range was found to be controlled by the interfacial reaction, while the reactivity with CO2 was controlled by both interfacial and diffusion which depended on the reaction temperature. The activation energy of coke gasification with H2O was up to 65% lower than that of CO2. However, this decrease was less pronounced for the high CSR coke, suggesting that a higher quality coke is required to mitigate the fast degradation of coke during reaction with steam.

Konstantin Weißhaar, AG der Dillinger Hüttenwerke, Germany

Abstract:
Since the coal market is very volatile and fast-moving, not only since the beginning of the energy crisis, rapid testing of alternatives for the coal blend of the Zentralkokerei Saar (ZKS) is indispensable. In this context, the most important tasks of a coke oven pilot facility are to investigate the effect of a test coal on the coke quality and the resulting wall pressure during the carbonisation. The latter parameter is of particular importance for the ZKS, as it is a coking plant using stamp charging operation with correspondingly increased wall pressures. For these reasons, the new ZKS coke oven pilot plant was built nearby the coke oven batteries in 2019. The optimization of the operating parameters took more time as expected. Especially the adjustment of the required coal cake density with a good homogeneity and the wall pressure measurement caused problems. By systematic modifications of the stamping program and the stamping machine, a satisfying density of 1020 - 1030 kg/m3 (dry) and homogeneity could be achieved. The homogeneity of the coal cake was investigated and quantified by core drilling and measurement of the individual layers. During the adjustment of the wall pressure measurement, a strong dependence on the ambient temperature was noticed, which initially amounted to almost 1 kN per °C temperature change. Through structural and procedural adjustments (stiffening of the mounting of the load cell, heating of oven walls, insulation of the wall pressure measurement), the temperature dependence could be reduced to 0.2 - 0.3 kN/°C. Nevertheless, the wall pressure results of the coking tests have to be corrected by a temperature correction function to minimize the error due to the temperature dependence.

Marc Schulten, thyssenkrupp Steel Europe AG, Germany

Co-Author:
Viktor Stiskala, thyssenkrupp Steel Europe AG
Alexander Sury, HUTNI PROJEKT Frydek-Mistek a.s.

Abstract:
thyssenkrupp Steel Europe successfully commissioned their pilot oven laboratory employing both a 10-kg carbonization retort and a 60-kg movable wall oven between the years 2014 and 2016. The installed facilities produce and deliver important timely information to coke plant operators who can profit from captive analysis results of internal gas pressure, wall pressure, and coke qualities obtained from actual coal blends and individual coals. Sufficient shrinkage of the coal charge in coke ovens is one of the most essential process conditions to ensure smooth oven pushing performance. As indirect findings on coal shrinkage behavior could only be derived from the results of the two pilot ovens, other considerations were reviewed. In view of the constantly changing conditions in the coal market coupled with the gradual ageing of coke ovens facing an elevated risk of refractory wear due to insufficient coal charge contraction control, the company decided to take another step towards securing their operational safety, prolonging the lifetime of the assets, and saving substantial resources in the maintenance budget. thyssenkrupp Steel Europe launched another major project in 2018 aiming at installing the sole heated oven as the only standardized tool for assessing coal shrinkage behavior when employing an internationally recognized test method. The company Hutni Projekt Frydek-Mistek was selected as the main contractor utilizing their long term experience with similar test facility installations, thus extending their previous successful co-operation with thyssenkrupp Steel Europe in the designing and commissioning of the 60-kg movable wall oven. The sole heated oven was put into operation in 2019. The objective of this paper is to outline the steps taken towards the successful commissioning and the resulting technical support to thyssenkrupp Steel Europe’s coke plant in Schwelgern.

Lorenzo Engel Fornasari, Ternium, Brazil

Co-Author:
Roberto Gerardo Bruna, Ternium
Camila Gisele Lalli, Ternium
Maite Ochoa, Ternium
Bruno Pinheiro da Silva, Ternium
Andres Aused, Ternium

Abstract:
Being able to accurately predict metallurgical coke properties for different parent coal blends is an important part of optimizing an integrated steelmaking plant production costs and ensuring blast furnace process safety. However, it is challenging to balance the economic pressures to use different coals and different blend compositions, the need for minimal product quality and the complexities of the coke-making process. The present work aims to construct coke quality models based on traditional analyses of constituent coals and some process parameters to enable better prediction for a wide range of blend characteristics. To this end, historical production data for process parameters and qualities of coke, coal and petcoke documented in a by-product coking plant were collected and processed using data mining and machine learning techniques. Attempts were made to model coke strength after reaction (CSR), stability and hardness indices by combining domain knowledge with feature engineering, feature selection algorithms and proposing three different models for each quality index - multiple linear regression, gradient boosted decision trees with XGBoost and gradient boosted linear trees with Light GBM. Cold strength models, especially those created using gradient boosting techniques, attained reasonable predictive ability. It is concluded that despite the inaccuracies surrounding industrial data collection, data mining and machine learning techniques provide a viable and promising framework for coke quality modeling in mature and well-documented processes.

Edward Bissaker, University of Newcastle, Australia

Co-Author:
Arash Tamesabi, University of Newcastle
David Jenkins, University of Newcastle
Merrick Mahoney , University of Newcastle
Bishnu Lamichhane , University of Newcastle

Abstract:
Metallurgical coke microstructure is highly variable and consists of features at a wide range of length scales. Understanding coke microstructure using 3D micro-CT analysis is a valuable tool for producing coke that meets the requirements of future steel-making technologies. The two-point correlation and lineal path functions are microstructure descriptors that can be used to distinguish between microstructure formations. We present a scalable, histogram-free parallel method to efficiently compute the angularly resolved two-point correlation and lineal path functions for large 3D coke microstructure images. We compute coke feature length scales and representative volume elements for coke microstructure and provide a quantitative framework for investigating optimal microstructures corresponding to coke strength.

Tetiana Rozhkova, Centre de Pyrolyse de Marienau, France

Co-Author:
Stéphanie Penerat, Centre de Pyrolyse de Marienau

Abstract:
“VITAL: Vitrinite Analysis” automatic measurement system of coal vitrinite reflectance, as well as maceral analysis was developed by working group composed of ArcelorMittal Dunkerque and Fos-Sur-Mer as well as ArcelorMittal Research SA and Centre de Pyrolyse de Marienau. The working group consisted of accredited by ICCP petrographer, plant and research specialists in coals and image analysis. VITAL system can be applied to all coking and semi-soft coking coals from 0,5% to 1,7% of vitrinite reflectance (i.e. reflectance in between lignite and anthracite coalification stages), of various organic and mineral composition (rich or poor in reactive vitrinite maceral group coals). The system offers rapid and automatic vitrinite reflectance and maceral analysis measurement with no intervention of experienced petrographer.

Ai Wang, University of Newcastle, Australia

Co-Author:
Bert Gols, Tata Steel Ltd
Tara Congo, The University of Queensland
Karen Steel, The University of Queensland
Arash Tahmasebi, The University of Newcastle
David Jenkins, The University of Newcastle

Abstract:
The addition of small fractions of non-coking coals into blends is often attractive to cokemakers, but there is the potential for reduction in coke quality. In particular, coke strength may be reduced due to poor quality IMDC-RMDC interactions. We investigate this issue using small coke samples with specifically chosen inertinite particles surrounded by vitrinite rich coal fractions. The coked samples are imaged using micro-CT and analysed to evaluate the quality of the interface. We present interactions between vitrinite-rich samples from 4 coking coals and inertinite particles from 4 non-coking coals. The results show that particular coking coal leads to poor quality interface with some non-coking coals.

Serhat Türkyılmaz, Ereğli Iron and Steel Works, Co., Turkey

Co-Author:
Erdal Ünal, Erdemir

Abstract:
Keywords: Plastic Waste, Cokemaking, Metallurgical Coke, Coke Production Coke is one of the main input raw materials of iron and steel production. Especially in blast furnaces, it is used as a heat source, reducing agent and burden supporter. In recent years, due to carbon emissions and environmental regulations, iron and steel factories are working on this subject. In this context, various studies are also carried out in cokemaking process, the use of plastic wastes in coke ovens is one of these studies. Plastic wastes can be used in coke ovens as a substitute for coal by adding certain proportions to the coal blend after several pretreatments. In this study, polyolefin-based HDPE (high density polyethylene) and polyaromatic-based PS (polystyrene) were added to the coal blend at 1% after briquetting with coal. The total briquetted coal ratio in the coal blend was set as 10%. Subsequently, the coking process was carried out in a laboratory scale coke oven with a capacity of 5 kg. Results showed that, with the addition of plastic waste to the coal blend, the reactivity and strength values of coke were not adversely affected, chemical and ash analyzes were found suitable for blast furnaces. However, the change in the amount of by-products in the coke process with the addition of plastic to the coal blend was investigated. It has been observed that each waste plastic has a different effect on coke by-products.

Christian Skelnik, thyssenkrupp Steel Europe AG, Germany

Abstract:
The coke plant Schwelgern uses nine to twelve different types of coal to produce a cokable feed mixture that meets operational safety, quality and economic requirements. The feed mixture is produced in a mixing bed using the chevron process. Procedural and logistical issues lead to inhomogeneities in the stacked mixing bed. The implementation of a control-based pile simulation model will detect and avoid these challenges through an adjusted stacking and planning strategy.