Oxidation and reduction characteristics of oxygen carrier particles and reaction kinetics by unreacted core model

Ryu, Ho-Jung; Bae, Dal-Hee; Han, Keun-Hee; Lee, Seung Yong; Jin, Gyoung-Tae; Choi, Jeong-Hoo

doi:10.1007/bf02705604

Cited by 108 publications

(84 citation statements)

References 11 publications

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“…The SCM has been able to predict experimental data for smaller particles [108,222]. However, uncertainty arises about the suitability of the SCM in these cases because of the high porosity and small size of the particles, in the order of 100 m.…”

Section: Shrinking Core Model (Scm)mentioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,963

1,614

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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.

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Section: Shrinking Core Model (Scm)mentioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,963

1,614

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“…Shrinking core model (SCM) for spherical grains has been used in literature to calculate kinetic parameters of NiO-based oxygen carriers [5,25,[34][35][36]38]. The particles are considered as a matrix of non-porous individual grains of uniform size.…”

Section: Kinetic Modelmentioning

confidence: 99%

“…Several works where the kinetics of reaction for the reduction with CH 4 , CO and H 2 and the oxidation with oxygen have been determined for Cu-, Ni-, Fe 2 O 3 -and Mn 3 O 4 -based oxygen carriers [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] can be found in the literature. Most of these experimental studies have been done in a thermogravimetric analyzer.…”

Section: Introductionmentioning

confidence: 99%

“…The kinetic parameters have been obtained using the shrinking core, the changing grain size and the nucleation models. Nevertheless, most of these studies carried out only a partial analysis without considering either the effect of the gas concentration or temperature [25][26][27][28][29][30][31][32][33][34]. In this case, limited information can be extracted from the reactivity data for design purposes, although they can be used to compare different oxygen carriers.…”

Section: Introductionmentioning

confidence: 99%

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Reduction and oxidation kinetics of nickel-based oxygen-carriers for chemical-looping combustion and chemical-looping reforming

Dueso

Ortiz

Abad

et al. 2012

Chemical Engineering Journal

168

114

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The kinetics of reduction with CH 4 , H 2 and CO and oxidation with O 2 of two NiO-based oxygen carriers prepared by impregnation, NiO18-Al and NiO21-Al, for chemicallooping combustion (CLC) and chemical-looping reforming (CLR) was investigated in this work. The experimental tests were carried out in a thermogravimetric analyzer using different reacting gas concentrations (5-20 vol. % for CH 4 , 5-50 vol. % for H 2 and CO and 5-21 vol. % for O 2 ) and temperatures (1073-1223 K). The reduction stage using both materials proceeded in two steps: a first period of high reactivity attributed to the presence of free NiO and then a low reactivity period that corresponded to NiAl 2 O 4 reduction. Therefore, the kinetic parameters for NiO and NiAl 2 O 4 reduction were determined separately for each oxygen carrier and each reacting gas. An empirical linear model was developed to describe NiO reduction. The solid conversion was a function of the fuel concentration and NiO content in the solid. The effect of temperature was low (E a ~ 5 kJ mol -1 ) although a chemical reaction rate controlled by diffusional processes was dismissed. The shrinking core model for spherical grain 2 geometry was used to obtain the kinetic parameters of the NiAl 2 O 4 reduction working with both NiO-based oxygen carriers. Chemical reaction control was assumed for NiO18-Al whereas diffusion through product layer was also considered when NiO21-Al was used as oxygen carrier. 82-472 kJ mol -1 activation energies were obtained with NiO18-Al particles. The activation energies were 237 and 373 kJ mol -1 for the kinetic constant and 200-281 kJ mol -1 for the diffusion coefficient, respectively, in the case of NiO21-Al oxygen carrier. Reduction reaction of NiO21-Al with CO was extremely slow and the kinetic parameters were obtained for comparison purposes with chemical control of the reaction rate. In this case, the reaction order was 1 and the activation energy 89 kJ mol -1 . The combined model for consecutive reduction of NiO and NiAl 2 O 4 in the NiO18-Al particles with the kinetic parameters obtained in this work predicted adequately the experimental results. The oxidation step of both oxygen carriers was fast and complete until reaching the initial condition. An empiric linear model, which assumes a linear relation between time and conversion, was developed to determine the kinetics of Ni oxidation. The reaction order of oxidation was about 0.8 for NiO18-Al and NiO21-Al and the activation energies were low, 22 kJ mol -1 in both cases. 

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“…For the kinetic modeling of this reaction they relied on an shrinking core model as proposed by Ryu et al [39] which is written in integral form as: …”

Section: Multi-phase Fluid Dynamicsmentioning

confidence: 99%

A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion

Kruggel‐Emden

Štěpánek

Munjiza

2011

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Impact du modèle de réaction sur les simulations CFD de la combustion en boucle chimique -La combustion en boucle chimique (Chemical Looping Combustion) est une technologie de combustion efficace permettant le captage in situ du CO 2 pour des charges gazeuses ou solides. Dans l'optique du développement et de l'extrapolation du procédé, la CFD est un outil de simulation à fort potentiel qui s'appuie notamment sur des modèles cinétiques pour décrire les réactions gaz-solide. Ces modèles décrivant les réactions sont généralement assez simples pour limiter les temps de simulation et sont obtenus à partir d'expérimentations en thermobalance. Il y a encore peu de travaux de modélisation CFD du procédé CLC et il est difficile d'estimer l'importance du modèle décrivant les réactions chimiques sur les résultats des simulations. Abstract -A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion -Chemical Looping Combustion is an energy efficient combustion technology for the inherent separation of carbon dioxide for both gaseous and solid fuels. For scale up and further development of this process multi-phase CFD-based simulations have a strong potential

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Oxidation and reduction characteristics of oxygen carrier particles and reaction kinetics by unreacted core model

Cited by 108 publications

References 11 publications

Progress in Chemical-Looping Combustion and Reforming technologies

Progress in Chemical-Looping Combustion and Reforming technologies

Reduction and oxidation kinetics of nickel-based oxygen-carriers for chemical-looping combustion and chemical-looping reforming

A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion

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