Coupling of shrinking core and Eulerian-Eulerian models for chemical looping combustion

One of the main barriers to the implementation of chemical looping combustion (CLC) on an industrial scale is the lack of knowledge about its operation at such scales. As a first step towards modeling industrial CLC devices, a consistent coupling between the shrinking core model (SCM) and the Eulerian-Eulerian multiphase framework with multicomponent phases was derived. This coupling enforces the constant volume assumption of a solid particle and allows for simple and consistent control of the oxygen transfer capacity. The derived approach was then applied to the chemical kinetic model of ilmenite redox reactions, which was sourced from the literature and was based on thermogravimetric analysis (TGA) data. Important corrections were made to the kinetic model parameters to ensure consistency with the present methodology, and the result was verified using a zero-dimensional TGA simulation setup. The methodology was further validated using experimental data from the literature for a laboratory-scale batch fluidized bed reactor. Three-dimensional simulations and an analytical one-dimensional quasi-steady-state model, derived on the basis of the coupling, have shown very close results to each other. However, as also previously observed in the literature, the conversion rates of H₂ were severely underestimated by the TGA-based kinetic model. Finally, the developed approach was applied to a 300 W CLC reactor, previously experimentally studied at Chalmers University. The agreement with the experimental data was reasonably good, but the reactivity of H₂ was higher than that reported in the experiments. The chemistry model source code and simulation configurations are made openly available.