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Experimental study and numerical simulation on porosity dependent direct reducibility of high-grade iron oxide pellets in hydrogen
Abstract
The transition to more environmentally friendly steel production methods has intensified research into hydrogen-based direct reduction (HyDR) of iron oxide pellets. The aim of this study is to systematically investigate the kinetics of the reduction process, the evolution of porosity and the resulting microstructural changes on the reduction behavior of high-quality pellets during HyDR of iron ore at different temperatures. A modified mathematical model is developed based on the shrinkage kernel model, taking into account both mass and heat transport in a hydrogen atmosphere. The effects of temperature, particle size and time on the reduction behavior of the pellets are investigated. The simulated results are validated and discussed by the results of a batch of iron oxide pellets consisting of ten almost spherical pellets subjected to the direct reduction process with pure hydrogen. The results show that the total energy input to the HyDR process is a complex balance of factors, including chemical reaction rates, diffusion dynamics and entropy generation. The increase in free volume and simultaneous decrease in pore diameter reflect the dynamic nature of the microstructure, which includes additional free volume and defects due to the volume discrepancies and associated stresses between the reactant and product phases. Furthermore, the data show that higher temperatures accelerate the reduction reactions, especially the transformation of wustite into metallic iron. This phase transition is characterized by a significant volume change that cannot be accommodated by elastic deformation alone, leading to the development of lattice defects such as cracks, creep pores and dislocations that serve as stress relief mechanisms. The trends for porosity change at 950 °C and 1000 °C observed in the experimental results are correct and in good agreement with the numerical and simulated results.
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Authors (6)
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Behzad Sadeghi
- Department of Innovation Engineering, University of Salento, Via per Arnesano, 73100, Lecce, Italy
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Pasquale Cavaliere
- Department of Innovation Engineering, University of Salento, Via per Arnesano, 73100, Lecce, Italy
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Mutlucan Bayat
- Department of Innovation Engineering, University of Salento, Via per Arnesano, 73100, Lecce, Italy
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Niloofar Ebrahimzadeh Esfahani
- Faculty of Electrical Engineering and Information, Slovak University of Technology, Ilkovicova 3, 81219, Bratislava, Slovakia
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Full text
- Publication version
- Accepted or Published Version
- DOI:
- Digital Object Identifier (open in new tab) 10.1016/j.ijhydene.2024.05.050
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Details
- Category:
- Articles
- Type:
- artykuły w czasopismach
- Published in:
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
no. 69,
pages 586 - 607,
ISSN: 0360-3199 - Language:
- English
- Publication year:
- 2024
- Bibliographic description:
- Sadeghi B., Cavaliere P., Bayat M., Ebrahimzadeh Esfahani N., Laska A., Koszelow D.: Experimental study and numerical simulation on porosity dependent direct reducibility of high-grade iron oxide pellets in hydrogen// INTERNATIONAL JOURNAL OF HYDROGEN ENERGY -Vol. 69, (2024), s.586-607
- DOI:
- Digital Object Identifier (open in new tab) 10.1016/j.ijhydene.2024.05.050
- Sources of funding:
-
- COST_FREE
- Verified by:
- Gdańsk University of Technology
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