@misc{FradetKurnatowskaRiedel, author = {Fradet, Quentin and Kurnatowska, Michalina and Riedel, Uwe}, title = {Thermochemical reduction of iron oxide powders with hydrogen: review of selected thermal analysis studies}, series = {Thermochimica Acta}, volume = {726}, journal = {Thermochimica Acta}, publisher = {Elsevier BV}, issn = {0040-6031}, doi = {10.1016/j.tca.2023.179552}, pages = {15}, language = {en} } @misc{AliMehlhoseFradetetal., author = {Ali, Mohammed Liaket and Mehlhose, Sven and Fradet, Quentin and Riedel, Uwe}, title = {An experimental and CFD study of the iron ore fixed bed structure and its influence on the direct reduction process}, series = {Proceedings of the 14th European Conference on Industrial Furnaces and Boilers}, journal = {Proceedings of the 14th European Conference on Industrial Furnaces and Boilers}, abstract = {The current circumstances of global warming, improved energy efficiency, and the higher suitability of Direct Reduced Iron (DRI) in Electric Arc Furnaces (EAF) for steel production necessitate a transition in the iron and steelmaking process from the traditional blast furnace/basic oxygen furnace to the more sustainable and eco-friendly direct reduction process. This reduction can be effectively studied in a fixed bed configuration, which bridges the gap between fundamental investigations on a single pellet and industrial shaft furnaces. While an average porous media model may be used to simulate the fixed bed reactor, this approach fails to account for the impact of intra- and inter-pellet fluid dynamics as well as heat and mass transfer. To accurately represent the geometric structure of iron ore pellet beds, an experimental construction must be accompanied by a particle-resolved CFD model. This article is divided into successive steps. The first step consists in the experimental construction of iron ore beds with different pellet size distributions (10-12.5 mm and 12.5-16 mm) and of the calculation of the bulk bed porosity and radial average bed porosity. The discrete element method (DEM) is further used to computationally reconstruct random packed beds of 0.5 kg industrial pellets based on the experimental data of pellet size distributions. A 3D domain is created using particle position data from the previous step, and pellets and voids are meshed at different refinement levels. Finally, CFD simulations are carried out to investigate the reduction of iron oxide pellets using H2 as a reducing gas in a fixed bed, considering available experimental data for model validation. The effect of three different bed structures on the overall conversion degree of iron ore is examined. This approach allows for successful modeling of a fixed bed using experimental input and investigation into the potential effects of the bed structure on the overall conversion during the direct reduction of the iron ore pellets.}, language = {en} } @article{NeumannFradetScholtisseketal., author = {Neumann, Jannik and Fradet, Quentin and Scholtissek, Arne and Dammel, Frank and Riedel, Uwe and Dreizler, Andreas and Hasse, Christian and Stephan, Peter}, title = {Thermodynamic assessment of an iron-based circular energy economy for carbon-free power supply}, series = {Applied Energy}, volume = {368}, journal = {Applied Energy}, publisher = {Elsevier BV}, issn = {0306-2619}, doi = {10.1016/j.apenergy.2024.123476}, pages = {23}, language = {en} } @misc{AliMehlhoseFradetetal., author = {Ali, Mohammed Liaket and Mehlhose, Sven and Fradet, Quentin and Riedel, Uwe}, title = {Particle-resolved computational modeling of hydrogen-based direct reduction of iron ore pellets in a fixed bed. Part II: Influence of the pellet sizes and shapes}, series = {International Journal of Hydrogen Energy}, volume = {86}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier BV}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.08.384}, pages = {1401 -- 1413}, language = {en} } @misc{AliFradetRiedel, author = {Ali, Mohammed Liaket and Fradet, Quentin and Riedel, Uwe}, title = {Particle-resolved computational modeling of hydrogen-based direct reduction of iron ore pellets in a fixed bed. Part I: Methodology and validation}, series = {International Journal of Hydrogen Energy}, volume = {87}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier BV}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.09.028}, pages = {332 -- 343}, language = {en} } @misc{FradetAliRiedel, author = {Fradet, Quentin and Ali, Mohammed Liaket and Riedel, Uwe}, title = {Development of a porous solid model for the direct reduction of iron ore pellets}, series = {steel research international}, volume = {93}, journal = {steel research international}, number = {12}, issn = {1869-344X}, doi = {10.1002/srin.202200042}, pages = {10}, language = {en} } @misc{FradetKuhnDeutschmannetal., author = {Fradet, Quentin and Kuhn, Carola and Deutschmann, Olaf and Riedel, Uwe}, title = {Towards carbon-free energy carriers: kinetics of the thermochemical reduction/oxidation of iron oxide/iron}, series = {18th International Conference on Numerical Combustion}, journal = {18th International Conference on Numerical Combustion}, abstract = {ron and its oxides are at the center of an innovative carbon-free chemical energy cycle within the Clean Circles research association. Energy can be stored within iron particles through the thermochemical reduction of iron oxide using green hydrogen; the stored energy is then released through the dust-firing of iron. Accurate kinetics models of both thermochemical processes are of prime importance for the design and operation of industrial systems. While the high-temperature oxidation of iron is a novel topic of research, many kinetic studies were already conducted on reducing iron oxide or iron ore. However, the discrepancies between studies are manifest, that it is in terms of reaction models, kinetic parameters, or even in terms of species involved. One of the issues is the simplicity of the mathematical models employed, based on linearization techniques of a limited number of thermogravimetric analysis (TGA) curves. The present work will tackle the kinetics of the thermochemical reduction/oxidation of iron oxide/iron utilizing the leastsquare method, allowing for a direct comparison between experiments and modeling. The experiments supporting the modeling will originate both from the literature and from our own measurements and will be of various types: isothermal TGA, TGA with linear heating rates, temperature-programmed reduction and X-ray diffractions. The influence of parameters, such as the particle size distribution or porosity, on the kinetics will be discussed.}, language = {en} } @misc{AliFradetRiedel, author = {Ali, Mohammed Liaket and Fradet, Quentin and Riedel, Uwe}, title = {Kinetic mechanism development for the direct reduction of single hematite pellets in H2/CO atmospheres}, series = {steel research international}, volume = {93}, journal = {steel research international}, number = {12}, publisher = {Wiley}, issn = {1611-3683}, doi = {10.1002/srin.202200043}, pages = {12}, abstract = {Increasing interest in the direct reduction process of iron ore has revived investigations on gaseous and heterogeneous iron oxides' kinetics. Despite extensive studies on the reduction of iron oxides with pure hydrogen or syngas, the development of a generic reduction mechanism for iron oxides is still lacking. The conventional shrinking core model hardly distinguishes between transport and reaction processes, leading to biases or even errors in the kinetic models. In the present study, a porous solid model, which solves mass balances of the individual gas-phase species and solid ones assuming spherical symmetry, is used for developing a heterogeneous kinetic mechanism accounting for different iron oxidation stages (Fe2O3, Fe3O4, FeO). It also accounts for carbon accumulation and cementite formation to model the carburization phenomena when using carbon-containing reducing agents like syngas. The proposed generic mechanism successfully reproduces 49 experimental data sets from the literature for single iron}, language = {en} }