Extended Euler–Euler model for the simulation of a 1 MWth chemical–looping pilot plant

Abstract

In chemical–looping combustion (CLC), the oxygen–carrier circulates between two interconnected fluidized beds. Experiments can provide substantial insight into the hydrodynamic behaviour of CLC, but are limited to the scale of the investigated pilot plant. Furthermore, the availability of detailed experimental information from pilot plants is difficult because of the lack of accessibility, the harsh environment and the costs of measuring devices. Computational fluid dynamics (CFD) offers a significant contribution to the direct measurements. A recent literature review shows that Euler–Euler CFD–based model has not yet been applied to chemical–looping combustion of coal. Therefore, a three–dimensional, transient simulation model for the fuel reactor of CLC has been developed. Besides the calculation of gas–solid flow, the model includes an accurate description of kinetic models for pyrolysis, heterogeneous reactions and related heat and mass transfer processes. The extended Euler–Euler/thermochemical reaction model is validated with measurements obtained from the world's second–largest CLC pilot plant (1 MWth) erected at TU Darmstadt. The numerical results suggest that the pressure drop in the fuel reactor, the exiting flue gas composition as well as the solid fuel conversion can be predicted reasonably. The validated model is of relevance for further feasibility and scale–up studies of CLC.