Sven Jensen, Dürr Systems AG, Germany

Abstract:
Gas prices in Europe will remain on a high level. Therefore, any gas fired process should be examined in regard to energy efficiency measures. Gas fired ovens are widely used in the steel industry. Very often the temperature of the exhaust gas at the stack is still in the range of 300 °C to 600 °C. The so called high-temperature ORC technology is an ideal tool to make use of that waste heat. Taking the example of an innovative ORC system installed at the site of a German steel mill, the lecture will present the achievements and challenges of two years of operation. In this project, the residual heat of the exhaust gases of a walking beam furnace is transferred in one-step to the ORC working media by using direct evaporation technology. As a consequence of capturing the thermal energy at high temperature levels of around 450 °C, the water-cooled condenser of the ORC system can be operated at an elevated temperature of up to 90 °C. The ORC system provides a two-fold benefit to the Customer. The turbogenerator feeds up to 500 kW electric power to the factory and, thus, reduces the expenses for purchasing power from the grid. Moreover, the ORC system transfers around 2.3 MW of heat to a district heating network. After commissioning in July 2020, the plant has been running several thousand operating hours. The presentation analyzes operating data and compares it to the project targets. Further explanations are given how the ORC system is integrated into the operational regime of the gas-fired walking-beam furnace. Finally, an exemplary economic calculation provides insights to the business case and highlights the benefits of an investment into a high-temperature ORC system as an energy efficiency measure: CO2 reduction, income from electricity produced, income from secondary thermal energy provided.

Björn Glaser, KTH Royal Institute of Technology, Sweden

Co-Author:
Marcus Holmström, KTH Royal Institute of Technology
Herbert Köchner, KTH Royal Institute of Technology/ASENSO
Daniel Sundberg, ScanArc Plasma Technologies AB
Asier Arteaga Ayarza, Sidenor Investigación y Desarrollo
Nora Egido Perez, Sidenor Investigación y Desarrollo
Raffaello Pio Iavagnilio, Politecnico di Bari

Abstract:
Marcus Holmström1, Björn Glaser1, Herbert Köchner2, Daniel Sundberg3, Asier Arteaga4, Nora Egido Perez4, Raffaello Pio Iavagnilio5 1Kungliga Tekniska Högskolan, Department of Materials Science and Engineering, Brinellvägen 23, 10044 Stockholm, Sweden 2ASenSo GmbH, Am Birkengraben 12, 50259 Pulheim, Germany 3ScanArc Plasma Technologies AB 4Sidenor Investigacion y Desarrollo SA 5Politecnico di Bari Keywords: Ladle preheating, plasma heating Preheating of steelmaking ladles is a prerequisite to minimize thermal shock and wear of the refractory and to reduce temperature losses of the liquid steel during tapping and holding times. Standard preheating technology using conventional gas-fired burners is unfavorable regarding thermal efficiency (5-15%), energy consumption and emissions. A novel technique using plasma heating offers a more flexible ladle preheating procedure with a higher thermal efficiency (80-95%) and aiming at reduced gas consumption and emissions. The current RFCS pilot and demonstration project PLASMAPILOT investigates the necessities, technical requirements and opportunities of ladle preheating procedures using plasma by combining measurements, numerical modelling of ladle preheating processes and pilot trials at a plasma heater test rig with a full-scale steelmaking ladle. First results will be presented on assessment of plasma technology with regards to economic and environmental benefits, together with results from plant trials and laboratory investigations on refractory lifetime.

Krzysztof Hornig, ANDRITZ Metals Germany GmbH, Germany

Co-Author:
Vasile Jechiu, ANDRITZ Metals Germany GmbH

Abstract:
Modern humankind will continue to need the products of the metal industry in the future, similar to the products of other key industries. Especially in the field of energy-intensive thermal processes in the steel industry, the high demand for process heat supplied today by the oxidation of fossil fuels is required in terms of process technology. The reversal from fossil fuels is the core task of the transformation towards sustainable thermal process technology. Therefore, traditional energy sources are replaced with CO2-neutral alternatives, i.e., green electrical energy and green hydrogen. On the path to sustainable thermal process technology, however, the following simultaneous efforts are fundamentally important as well: • A further increase in the thermal efficiency of the process while reducing emissions as harmful as NOx or dust emissions. • A reduction in material loss within the production chain. For example, material loss occurs during the heating process due to scale formation. • An optimal interlinking of the individual production steps to increase the production chains' overall efficiency. • All-round use of intelligent, connected, and user-friendly automation systems. These measures have a particularly sustainable effect in modernizations and upgrades, where omitting additional cumulative CO2 emissions due to the reuse of the already produced assemblies improves CO2 balance of the retrofitting effort. In the article, the innovative and practical solutions for heating systems in industrial furnaces for the steel industry are presented with the help of concrete examples. Furthermore, the complexity of the requirements for the industrial heating systems is analyzed. In particular, the latest developments with regenerative burners and hybrid heating systems

Stefan Albers, PSI Metals GmbH, Germany

Abstract:
With increasing share of renewable energy, energy availability will become more volatile. To respect resulting energy consumption constraints from energy providers, to contribute to grid stability and reduce energy costs, we need to forecast energy consumption cross-line in the production planning and scheduling process. This requires product and process specific forecasting models for all operations. PSI Metals applies these models to forecast and optimize cross-line schedules respecting energy availability constraints. Using a KPI driven Qualicision solver, automated energy procurement buys and sells in day-ahead and intra-day trading. This enables easy adaptation to changes in consumption forecasting whenever production plans are altered due to actual situations. It further enables energy procurement to cash in on short-term energy prices. This paper outlines deriving the forecasting models from production and EMS data as well as the combination of detailed forecasting with KPI-driven automated energy trading systems.

Jonas Oswald, Dürr Systems AG, Germany

Abstract:
In a world of limited resources, the reuse of materials plays an important role for building a circular economy. An established process in the recycling industry for removal of impurities from steel and metal pieces is the pyrolysis process. Hydrocarbons are removed at elevated temperatures. The process generates excess heat if the syngas produced is being utilized as input fuel. The usage of this excess heat for electricity production and, if required, for providing useful heat is a significant step to lower the Carbon footprint in these processes and additionally to reduce the operating costs. Dürr Cyplan has executed a best practice example which can be the blueprint regarding energy efficiency for the above-described processes in the steel industry. In this project shredded Aluminum waste is being processed in a rotary kiln (pyrolysis reactor) and purified to high grade Aluminum granulate. The rotary kiln is fired with the flue gases of the burned syngas that was generated in the pyrolysis process. The remaining excess heat from the flue gases is utilized in a high temperature ORC process at a temperature level of ~500°C. The Dürr Cyplan high temperature ORC-module can cover the own consumption of electricity for the whole purification process line and can additionally cover partially the demand of electricity of the whole factory. This brings a saving of ~140tons of CO2 annually* and lowers the electricity bill significantly. The described operating principle can be applied for the upgrading of metal and steel waste. Dürr Cyplan ORC modules can utilize heat with different interfaces to convert high temperature heat into electricity and additionally useful heat for follow up processes. This operating principle can be described as an electricity producing heat exchanger and can be applied in various process steps within the variety of metal and steel processing.

Frank Mintus, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Susanna Bosi, ergolines lab s.r.l.
Loris Bianco, Feralpi Group
Matthew Phillips, Cardiff University
Min Gao, Cardiff University
Piero Frittella, ESF Elbe-Stahlwerke Feralpi GmbH
Tim Bause, ESF Elbe-Stahlwerke Feralpi GmbH
Nils Katenbrink, Quick-Ohm Küpper & Co. GmbH
Luca Petrucci, Centro Sviluppo Materiali SPA
Luca Innocenzi, Centro Sviluppo Materiali SPA
Ugo Chiarotti, Centro Sviluppo Materiali SPA
Matteo Chini, Feralpi Group
Daniele Gaspardo, Feralpi Group

Abstract:
In the steel industry, large amounts of waste heat are generated in nearly all steps of the steelmaking process. The recovery of this waste heat could be a key technology on the way to net-zero steel production. Various technologies are available for this purpose, including the use of thermoelectric systems for power generation. The research project InTEGrated (Funded by EU-RFCS Programme, No. 899248) investigates the use of thermoelectric generators (TEGs) to recover thermal energy from two different waste heat sources: 1) EAF cooling water circuit and 2) radiation from steel products. Small prototypes were developed and initially tested in the laboratories. Based on the laboratory results and simulations, advanced prototypes were developed and installed for long-term tests at the EAF cooling water system at Ferriere Nord (Italy) and at the hot rolling mill of ESF Elbe-Stahlwerke Feralpi in Germany. Prototype design, results of prototype laboratory tests, simulation results and initial outcomes of the long-term tests are presented.

Martin Hubrich, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Matthias Kozariszczuk, VDEh-Betriebsforschungsinstitut GmbH

Abstract:
In Germany, 85% of the total non-public water supply of 14 billion m³ (2019) is used in the area of plant and product cooling. Due to climate change, a continuous limitation of water withdrawal and wastewater discharge quantities in combination with increasing temporary or permanent water shortage can be observed, which can lead to a potentially negative impact on production or plant availability, especially in cooling and casting processes. Strongly varying cooling water and concentrate compositions (salts, hardening agents) as well as certain ingredients (e.g. organics) prevent the closing of the cycles or recycling. Innovative and easy-to-use desalination processes such as membrane-based capacitive deionization are available but have not yet been adapted to the requirements of the iron and steel industry with regard to the complex water matrix. As a result, there is a need for solutions to deal with these temporary situations by using wastewater as an alternative water source to ensure the water supply and developing suitable process approaches for producing mono concentrates from the desalination concentrate as a prerequisite for material recycling. For this purpose, the use of membrane-based capacitive deionization, which has already been successfully tested in the field of cooling water treatment, is considered in more detail. The focus of the current BFI work is the treatment of organic and solid-containing wastewaters from chemical-physical treatment plants or biological treatment plants for the treatment of degreasing baths and old emulsions as well as a for a central treatment plant before discharge. Another focus is the determination of potential impurities and their removal to ensure reliable and energy-efficient process technology for wastewater desalination. At the same time, the production of mono-concentrates from the resulting mixed concentrates for the electrochemical production of a chlorine-based biocide for direct use in cooling circuits is being investigated.

Jovana Gradinac, SMS group, Italy

Co-Author:
Nadalutti Andrea, SMS group

Abstract:
Water present elementary necessity of life and it may seem inconceivable to imagine living without it. The environmental impact, together with social and economic impact of past and traditional water treatments in steel industry and inevitable fact of water scarcity are leading and driving shift to a new paradigm in a water treatments. Now days, many communities and countries are approaching the limits of their available water supplies and because of that, many steel industry plants are facing a big problem with water availability. Although water reclamation and reuse is practiced in many countries around the world, current levels of reuse constitute a small fraction of the total volume of industrial effluent generated. In addition, to meet their growing water supply needs, communities are considering other non-traditional sources of water which could lead to water saving. Water reclamation and its reuse have become an attractive option for conserving and extending available water supply by potentially applying different solution based on biological, chemical and mechanical improved solutions. Since these trends are emerging developments in the field of water reclamation and reuse, there are a number of research needs associated with these topics. Here proposed research is needed to better understand the issues present in traditional water treatment plants in steel industry, to propose and explain innovative technologies, which are improving traditional solutions of the water treatment plants, and to develop tools and other assistance for the steel industry to implement successful water reclamation and reuse projects.

Matteo Tomba, PERT Srl, Italy

Abstract:
A new steelmaking facility was built in a desert region for the production of 1.500.000 t/y of steel billets. Severe problems of water scarcity greatly affect the cooling water auxiliary plant. Following the traditional sizing criteria the need of more than 650 m3/h of raw water consumption was estimated, as peak hourly value. To meet the target of maximum 250 m3/h of available water in site, a not-conventional approach was necessary. Cooling equipment with low water consumption and internal recycle of treated water drains has been adopted. Conversely high investment cost and electrical energy consumption will be suffered. The solution finally results also economically interesting, especially thanks to the water chemical conditioning saving and could be applicable in other industrial realities.