Estimation and modeling of parameters for direct reduction in iron ore/coal composites: Part II. Kinetic parameters

Donskoi, E.; McElwain, D. L. S.; Wibberley, L. J.

doi:10.1007/s11663-003-0012-2

Cited by 60 publications

(53 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was widely assumed that the metal oxides reduction by carbon should be negligible at temperatures lower than 1000 ºC [367][368][369]. However, Siriwardane et al [227,370] showed the direct reduction Even though N 2 was used as fluidizing gas, eventually the char conversion through CO 2 gasification can be the relevant reacting mechanism.…”

Section: Reaction Schemementioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,999

1,614

View full text Add to dashboard Cite

This work is a comprehensive review of the Chemical-Looping Combustion (CLC) and Chemical-Looping Reforming (CLR) processes reporting the main advances in these technologies up to 2010. These processes are based on the transfer of the oxygen from air to the fuel by means of a solid oxygen-carrier avoiding direct contact between fuel and air for different final purposes. CLC has arisen during last years as a very promising combustion technology for power plants and industrial applications with inherent CO 2 capture which avoids the energetic penalty present in other competing technologies.CLR uses the chemical looping cycles for H 2 production with additional advantages if CO 2 capture is also considered.The review compiles the main milestones reached during last years in the development of these technologies regarding the use of gaseous or solid fuels, the oxygen-carrier development, the continuous operation experience, and modelling at several scales. Up to 2010, more than 700 different materials based on Ni, Cu, Fe, Mn, Co, as well as other mixed oxides and low cost materials, have been compiled. Especial emphasis has been done in those oxygen-carriers tested under continuous operation in Chemical-Looping 2 prototypes. The total time of operational experience (≈ 3500 h) in different CLC units in the size range 0.3-120 kW th , has allowed to demonstrate the technology and to gain in maturity. To help in the design, optimization, and scale-up of the CLC process, modelling work is also reviewed. Different levels of modelling have been accomplished, including fundamentals of the gas-solid reactions in the oxygen-carriers, modelling of the air-and fuel-reactors, and integration of the CLC systems in the power plant. Considering the great advances reached up to date in a very short period of time, it can be said that CLC and CLR are very promising technologies within the framework of the CO 2 capture options.

show abstract

Section: Reaction Schemementioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,999

1,614

View full text Add to dashboard Cite

show abstract

“…The main chemical reactions resulting from heating such composites are the coupled gaseous reduction of iron oxides (1) and gasification of carbon or Boudouard reaction (2) As these reactions occur in series, one or the other can control the overall reaction rate in the self-reducing composites depending on a variety of experimental conditions such as the composition (oxide to carbon ratio), form (pellet, briquette, packed bed) and size of agglomerate, the heating regimes and the surrounding atmosphere composition and pressure. As reviewed by Donskoi et al, 10) a vast majority of researchers claim the Boudouard reaction as a limiting step of a self-reduction process. [11][12][13][14][15] Others propose a mixed control regime with the influence of both reactions (gasification and reduction)or a mixed gasification and heat transfer control regime.…”

Section: Introductionmentioning

confidence: 99%

“…The relatively high activation energy values (250-350 kJ/mol) are taken as being characteristic for the Boudouard reaction control while the lower values indicate an increasing role of reduction in overall self-reduction rate control. 10,14) Accord- ing to Iguchi et al [22][23][24] the carburization of freshly reduced iron by direct carbon dissolution C(s) = [C] is another important reaction which could interfere in self-reduction, especially at the reduced pressures and high temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…10,[22][23][24][25][26][27] On the other hand, the hematite and magnetite ores, synthetic wustite as well as some waste materials (EAF dust, mill scale) were used as the iron oxide bearing materials in the self-reducing mixtures and agglomerates. 10,11) In addition to the reaction rate limits, another important issue is the mechanical strength of the agglomerates during the reduction. It depends to a large extent on the morphology of the resulting iron, which can lead to some adverse effects such as swelling and cracking of agglomerate.…”

Section: Introductionmentioning

confidence: 99%

“…[28][29][30] The mechanism and kinetics of self-reduction has already been modelled to better understand the rate phenomena and to optimize the iron oxide/carbon composite technology by better selection of constituents and their processing conditions. 10,[18][19][20][21]24) These models take into consideration not only the kinetics of gasification and reduction reactions but also the mass and heat transfer phenomena and balances. They need precise measures of the involved reactions rate constants and some structural parameters (porosity, specific surface, etc.)…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Carbon Gasification in Self-reducing Mixtures

et al. 2014

View full text Add to dashboard Cite

Self-reduction experiments of mill scale with four potential carbonaceous reductants (charcoal, coal char, blast furnace coke and petroleum coke) were carried out by thermogravimetry (TG) in order to choose one allowing the highest reduction rate and overall conversion. The fastest rate of self-reduction was measured for the charcoal and the slowest for the petroleum coke. The Friedman method of kinetics data analysis was used to calculate apparent activation energy at different conversion rates. Based on these values it can be concluded that the Boudouard reaction controls the rate of self-reduction with charcoal up to about 60% of conversion and even more for others reductants. It has also been demonstrated that the morphology of the iron produced strongly depends on reactivity of carbonaceous reductant.

show abstract

Kinetics of the Reactions Prevailing during Packed‐Bed Chemical Looping Combustion of Syngas using Ilmenite

et al. 2016

View full text Add to dashboard Cite

Chemical looping combustion has been identified as a very promising technology for power production with integrated carbon dioxide capture. The objective of this work is to study the kinetics of all reactions that are important in the combustion of syngas in a packed‐bed chemical looping reactor by using ilmenite as an oxygen carrier. The reaction kinetics of reduction, with hydrogen and carbon monoxide, and oxidation, with oxygen, of ilmenite‐based pellets have been determined in a thermogravimetric analyzer. The shrinking core model for a spherical geometry was used to obtain the kinetic parameters by considering mixed control by chemical reactions and diffusion through the product layer for all reaction involved. The reduction rate of ilmenite by hydrogen was at least an order of magnitude higher than that by carbon monoxide (especially at higher particle conversions) and the activation energies were found to be 45 and 30 kJ mol−1 for reduction with hydrogen and carbon monoxide, respectively. For the oxidation reaction, a much lower apparent activation energy of 5 kJ mol−1 was found, which indicated that the temperature did not have an important effect on the oxidation kinetics of ilmenite. In addition, the catalytic activity of ilmenite for water gas shift (WGS) was measured in a micro fixed‐bed reactor. An empirical power‐law model was used to describe the kinetics of the WGS reaction over ilmenite.

show abstract

Estimation and modeling of parameters for direct reduction in iron ore/coal composites: Part II. Kinetic parameters

Cited by 60 publications

References 50 publications

Progress in Chemical-Looping Combustion and Reforming technologies

Progress in Chemical-Looping Combustion and Reforming technologies

Carbon Gasification in Self-reducing Mixtures

Kinetics of the Reactions Prevailing during Packed‐Bed Chemical Looping Combustion of Syngas using Ilmenite

Contact Info

Product

Resources

About