Modeling and Simulation of Isothermal Reduction of a Single Hematite Pellet in Gas Mixtures of H2 and CO

Beheshti, Reza; Moosberg-Bustnes, John; Aune, Ragnhild E.

doi:10.1007/978-3-319-48237-8_60

Cited by 10 publications

(23 citation statements)

References 12 publications

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“…This is also stated by [13}. Also, [14] established that an increase in the reduction temperature resulted in an increase in the reduction rate. However, it is noted that an increase in rate may not mean an increase in metallization because of the complex effects of equilibrium on metallization.…”

Section: Temperature Of Reducing Gases and Oxide Feedsupporting

confidence: 62%

Modeling of Reduction of Itakpe Oxide Pellets in Furnace Reactor

O¹,

E²

2021

IJEAST

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The multiple gas solid reactions, the physico-chemical, transport and thermal phenomena taking place in the Direct reduction furnace of the Delta Steel plant was modelled using the shrinking core model on Itakpe ore with a view to improving on the efficiency of the reduction process. The mathematical description of the detailed physical, chemical, transport and thermal phenomena occurring in the furnace was carried out and the models described the fluid/solid flows through the moving bed reactor system and was conjugated with heat transfer, specie transport which included the solid oxide pellet feed and the reducing gases. The effect of the diffusion resistances, the intra-particle diffusion and kinetic phenomena coupled with other operating parameters on the overall particle conversion were examined and the Shrinking Core Model was able to correctly describe the heterogeneous process. The models were validated with data obtained in the reduction of the local Itakpe iron ore pellets. The simulated particles in this process was the 1.2cm diameter Itakpe pellet. The results of the reduction of the Itakpe iron ore were in close conformance with the behaviour of most worldwide iron oxides used in the direct reduction process.

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Section: Temperature Of Reducing Gases and Oxide Feedsupporting

confidence: 62%

Modeling of Reduction of Itakpe Oxide Pellets in Furnace Reactor

O¹,

E²

2021

IJEAST

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“…The present authors previously developed, and experimentally validated, a model for the reduction of a single pellet of hematite. 19 The previous model could reproduce the experimental results for single pellets with reasonable accuracy. In the current model development, the previous work is extended to account for the reduction of pellets in a fixed bed.…”

Section: Introductionmentioning

confidence: 88%

“…As the first step, a model for the reduction rate of a single pellet was developed, and has been reported elsewhere. 19 This isothermal model was based on the Shrinking Core Model (SCM) 20-24 for gas-solid reactions. The model considered the diffusion in the porous haematite pellet, as well as in the product layers, and the equations were solved by Finite Element Modelling (FEM) using the commercial COMSOL Multiphysics® software (Version 4.3b).…”

Section: 15mentioning

confidence: 99%

“…The present model is based on the following assumptions 15,19 : The pellet is considered to be isothermal, spherical and possessing uniform porosity. The mass resistances through the film around the pellet are negligible. Reactions are irreversible: first order and precede topochemically. The reduction rate is controlled by one of the following: The diffusion of H 2 and CO through the porous solid. Chemical reaction with the solid oxides in the interior of the pellet. Diffusion of the larger gaseous product molecules of H 2 O and CO 2 away from the reaction surface and through the solid porous layer. During the reduction process, there is no change in the pellet diameter, and no cracking takes place. The total pressure is uniform inside and around the pellet. The catalytic effects are negligible. The gas is considered an ideal mixture. Details of the single pellet model are given elsewhere. 19…”

Section: Model Developmentmentioning

confidence: 99%

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Reduction of commercial hematite pellet in isothermal fixed bed—experiments and numerical modelling

Beheshti

Moosberg-Bustnes

Kennedy

et al. 2016

Ironmaking & Steelmaking

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In the present work, fixed bed reduction experiments were conducted at 1173 K over a range of H 2 /CO ratios from 0.8 to 2.0 and subsequently modelled numerically. The model consists of two one-dimensional, isothermal and time dependent models. The gas-solid reactions were kinetically modelled using a modified shrinking core approach, and the equations were solved using the commercial software COMSOL Multiphysics H . The simulation results agree with thermal gravity experimental data with an average difference of 2.5%. A sensitivity analysis was conducted using the numerical model to establish the optimum operational conditions. The effects of the reducing gas ratio and flow rate, pellet radius and porosity, and the total bed height on the overall degree of reduction were also investigated.

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“…The time needed to reach an oxidation fraction of γ Ox = 0.8 drops from 41.8 min with S1 down to 26.8 min with S2, implying a decrease of the oxidation time of 36%, as illustrated in Figure 7. Indeed, increasing the pellet size results in slowing down the solid state diffusion and, consequently, the reaction kinetics [43,47].…”

Section: Effect Of the Pellet Sizementioning

confidence: 99%

On the Development of Thermochemical Hydrogen Storage: An Experimental Study of the Kinetics of the Redox Reactions under Different Operating Conditions

2021

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This work aims at investigating the reduction/oxidation (redox) reaction kinetics on iron oxide pellets under different operating conditions of thermochemical hydrogen storage. In order to reduce the iron oxide pellets (90% Fe2O3, 10% stabilizing cement), hydrogen (H2) is applied in different concentrations with nitrogen (N2), as a carrier gas, at temperatures between between 700∘C and 900∘C, thus simulating the charging phase. The discharge phase is triggered by the flow of a mixture out of steam (H2O) and N2 at different concentrations in the same temperature range, resulting in the oxidizing of the previously reduced pellets. All investigations were carried out in a thermo-gravimetric analyzer (TGA) with a flow rate of 250mL/min. To describe the obtained kinetic results, a simplified analytical model, based on the linear driving force model, was developed. The investigated iron oxide pellets showed a stable redox performance of 23.8% weight reduction/gain, which corresponds to a volumetric storage density of 2.8kWh/(Lbulk), also after the 29 performed redox cycles. Recalling that there is no H2 stored during the storage phase but iron, the introduced hydrogen storage technology is deemed very promising for applications in urban areas as day-night or seasonal storage for green hydrogen.

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Modeling and Simulation of Isothermal Reduction of a Single Hematite Pellet in Gas Mixtures of H2 and CO

Cited by 10 publications

References 12 publications

Modeling of Reduction of Itakpe Oxide Pellets in Furnace Reactor

Modeling of Reduction of Itakpe Oxide Pellets in Furnace Reactor

Reduction of commercial hematite pellet in isothermal fixed bed—experiments and numerical modelling

On the Development of Thermochemical Hydrogen Storage: An Experimental Study of the Kinetics of the Redox Reactions under Different Operating Conditions

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