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Model is predictive of the exit gas composition of the literature data. Analysis of the sensitivity of model predictions to hydrodynamic parameters. The effect of reactor hydrodynamics on CLC performance is explored. a b s t r a c t A three-phase hydrodynamic model is employed for the analysis of experimental data of chemicallooping reduction with nickel-based oxygen carriers and methane as the fuel. The model rigorously accounts for the mass, energy, and pressure balances, and the effect of oxygen carrier entrainment in the freeboard region. Model predictions are in good agreement with the relevant experimental data. The capability of the model to be used in the scale-up of fixed-bed kinetic studies of oxygen carriers to fluidized bed pilot-scale reactors is illustrated. The generality and validity of the model are analyzed, so that it can be used for further reactor design studies. In particular, sensitivity analyses, in terms of the crucial hydrodynamic parameters and correlations are carried out and the effects of important parameters, such as bubble size, mass transfer, oxygen carrier entrainment and reactions in the freeboard, on the performance of the chemical-looping reducer are investigated.

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There is significant controversy in the reduction kinetics of chemical-looping combustion (CLC) between NiO and CH 4 . We propose an application of a model-based framework to improve the quality of CLC experiments with respect to model discrimination and parameter estimation. First, optimal experiments are designed and executed to reject inadequate models and to determine a true model structure for the reaction kinetics of the CH 4 -NiO system. Then, kinetics with statistical significance is estimated from experiments aimed at reducing parameter uncertainty. To maximize the observability of the NiO reduction reactions, fixed bed experiments should exhibit a peak separation of the concentration profiles, an initial high methane slip, and low overall CO 2 selectivity. Several case studies are presented to check the adequacy of the recommended model and evaluate its predictive ability and extrapolation capabilities. The model resulting from this work is validated and suitable for application in process design and optimization.

This paper presents an experimental study of high-pressure chemical-looping combustion (CLC) of methane and synthesis gas using supported Cu and Ni oxygen carriers. The experiments were performed in an isothermal, fixed-bed reactor at the pressure range of 1–10 bar. The analysis showed that at elevated pressures, the reactivity of the CLC oxygen carriers deviates from that at atmospheric pressure. Formation of solid carbon was found favorable at high pressures for both oxygen carriers, though more extensively with Cu materials. An empirical kinetic model was used to capture the effect of pressure on the reduction and oxidation reactions. The objective of this work is to derive a kinetic model that can accurately capture the idiosyncrasies of high-pressure CLC, which can guide process design studies of CLC integration into power plants.