Model‐based analysis of chemical‐looping combustion experiments. Part II: Optimal design of CH₄‐NiO reduction experiments

Abstract

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.

Numerical Modeling of Oxygen Carrier Performances (NiO/NiAl2O4) for Chemical-Looping Combustion

“…The most-used models are the unreacted shrinking core model (SCM), the modified volumetric model (MVM) and the nucleation growth model (NGM) [23][24][25]. In particular, these investigations used and compared the different models to each other for simulating different CLC processes.…”

“…In particular, these investigations used and compared the different models to each other for simulating different CLC processes. Indeed, Han et al [25] investigated the oxidation of hydrogen by a Ni-based oxygen carrier in TGA apparatus. These authors studied the effect of particle size to examine the diffusion limitation, the effect of cyclic testing and the binder reactivity.…”

Dynamic optimization of fixed bed chemical-looping combustion processes

“…We utilized optimal experimental design methods to statistically verify the CLC kinetic models and in turn, maximize the fidelity of the kinetic model to predict data outside of its design space. 63,64 We performed high-pressure fixed bed experiments with Cu-and Ni-based oxygen carriers and matched the data using an empirical pressure correlation 65 and the optimized kinetic models derived at atmospheric pressure. 66 Thus, we can conclude that the reactor and kinetic models used here are realistic and accurate enough for depiction of the large-scale fixed bed systems analyzed here.…”

Dynamic Simulation of Fixed‐Bed Chemical‐Looping Combustion Reactors Integrated in Combined Cycle Power Plants

“…The Ergun equation was used for the momentum balance. The reaction kinetics was derived from atmospheric‐ and high‐pressure gaseous CLC experiments that used supported Ni‐ and Cu‐based oxygen carriers . This model was developed by using gPROMS and was used successfully for the prediction of CLC data over a range of operating pressures, temperatures, and fuel compositions.…”

“…Ther eactionk inetics was derived from atmospheric-a nd high-pressure gaseous CLC experiments that used supported Ni-and Cubased oxygen carriers. [31,[57][58][59][60][61][62][63][64] This modelw as developed by using gPROMS [27] and was used successfully for the prediction of CLC data over ar ange of operating pressures,t emperatures,a nd fuel compositions. Specifically,t his model was validated against ar ange of particle sizes and temperatures tested in the literature with the use of variouss upported Niand Cu-based oxygenc arriers.…”