Analysis of fixed bed data for the extraction of a rate mechanism for the reaction of hematite with methane

Breault, Ronald W.; Monazam, Esmail R.

doi:10.1016/j.jiec.2015.03.020

Cited by 10 publications

(20 citation statements)

References 34 publications

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“…These data will be analyzed in more detail below to extract kinetic rates for CFD modeling of chemical looping process configurations. This first cycle is used as it was shown by Breault and Monazam [27] that the first cycle in these batch tests behaved like multiply cycled carrier in fluidized bed tests. The effect of the oxygen concentration used in the tests is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Based upon the results from the reduction analysis [27][28][29] and the findings from Monazam et al [26], a conceptual model of the re-oxidation process can be put together that demonstrates the re-oxidation process based upon the above findings. The carrier particle consist of grains with large pours that do not affect the concentrations within the particle (lower left of Fig.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…Therefore, in light of these findings, the objective of this work was to conduct a detailed analysis of the carrier re-oxidation process to develop an engineering kinetic model for the re-oxidation of reduced hematite. Furthermore, in the work by Breault and Monazam [27] they show that heat liberated in the particle during the first reduction cycle significantly changes the particle morphology in the fixed bed work and not in fluidized beds due to the higher heat transfer rates. Therefore, the kinetic analysis is done only on the first cycle from each test series.…”

Section: Introductionmentioning

confidence: 97%

“…The rapid commercialization and deployment of chemical looping technology using ores necessitates the need for engineering models for the reduction and re-oxidation steps that can be used in CFD simulations being done at the Department of Energy. These models for the reduction step were developed and can be found in the work by Breault and Monazam [27]. Therefore, in light of these findings, the objective of this work was to conduct a detailed analysis of the carrier re-oxidation process to develop an engineering kinetic model for the re-oxidation of reduced hematite.…”

Section: Introductionmentioning

confidence: 99%

“…The temperature is kept at approximately 800°C, except for an approximately 15°C increase during regeneration. Details of the operation can be found in Breault and Monazam [27].…”

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Analysis of hematite re-oxidation in the chemical looping process

Breault

Monazam²,

Carpenter

2015

Applied Energy

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h i g h l i g h t sRe-oxidation of Fe 2 O 3 CLC carrier is examined to assess O 2 and temperature. A two process step model has been developed -grain surface and grain core. Grain surface oxidizes which transports oxygen to the core by vacancy diffusion. The surface model is 1st order with a tendency toward nucleation with 1-D growth. The model for the core corresponds to nucleation with 2-dimentional growth. a b s t r a c tVery little attention has been dedicated to the carrier re-oxidation in chemical looping systems. The work presented in this paper is for the re-oxidation of partially reduced hematite from a cyclic chemical looping fixed bed process. The underlying purpose of this work is to develop engineering rates and mechanisms for the re-oxidation of partially reduced hematite that can be included in CFD models for a chemical looping process. To this end, experiments were run using nominally 1000 g of hematite material in a fixed bed reactor cycling between reduction and re-oxidation. The cyclic processing began with the reduction step then proceeded to the oxidation step repeating this analysis for several cycles ranging from 5 to 10. The re-oxidation process was conducted at temperatures ranging from 745°C to 825°C and oxygen concentrations ranging between 9% and 11%. The reduction was carried out at the same temperature as the re-oxidation step at various CH 4 concentrations from 5% to 9%. In this paper, cyclic induced variations in performance are presented as well as the kinetic parameters for the first cycle. The re-oxidation of the depleted hematite occurs through a 2 step parallel process in which oxygen reacts to fill the surface of each grain within the particles and then migrates through oxygen vacancy diffusion to the depleted cores of each grain.Published by Elsevier Ltd.

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Section: Resultsmentioning

confidence: 99%

Section: Analysis and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

“…The temperature is kept at approximately 800°C, except for an approximately 15°C increase during regeneration. Details of the operation can be found in Breault and Monazam [27].…”

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confidence: 99%

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