A new grain model for the redox reactions of copper-based oxygen carriers was proposed. It can predict the development of conversion, porosity and surface area over time taking into account the effects of the grain size distribution and sintering simultaneously. This model has population balance equations, which were solved by using a variation of the extended method of moments (EMOM) with regularization. A simplified solution that requires minimal computational effort was derived, which can be incorporated in models of Chemical looping processes at real scale.
In order to verify the model, six copper-based oxygen carriers were synthesized by wet-impregnation and incipient wetness impregnation. They were characterized by BET surface area, BJH porosimetry, X-ray diffraction (DRX) and SEM microscopy. Model results were compared with experimental data taken from thermogravimetric measurements in several redox cycles. The model predicted the experimental data accurately, including the "die off" phenomenon which occurs at low temperatures, and the drop in conversion due to sintering that is observed with the course of redox cycles. Moreover, it was shown the importance of taking into account the grain size distribution and the sintering effect by making a comparison between the model of this paper and the classic changing grain size model.
Finally, It was found that copper-based oxygen carriers synthesized using incipient wetness impregnation were affected more strongly by the sintering over the course of redox cycles, than the ones prepared via wet-impregnation.
Acknowledgments: The authors wish to thank the" Administrative Department of Science, Technology and Innovation "- Colciencias (Administrative Department of Science, Technology and Innovation from Colombia) Through the program" Research on innovation in advanced combustion Industrial use "code No. Contract No. 0852-2012 1115-543-31906
See more of this Group/Topical: Topical Conference: Innovations of Green Process Engineering for Sustainable Energy and Environment