화학공학소재연구정보센터
Energy & Fuels, Vol.31, No.11, 12466-12476, 2017
Dynamic Coupling of Pore Structure Evolution with Carbonation Kinetics of CaO-Based Sorbents: Experiments and Modeling
The microstructure and pore structure evolution of CaO-based sorbents in three particle size ranges of 0.075-0.1, 0.15-0.18, and 3 mm were investigated using field emission scanning electron microscopy with energy dispersive spectroscopy and nitrogen adsorption-desorption techniques. A clear heterogeneous distribution of elemental carbon across the sorbent particles was found. A particle carbonation reaction model considering the structural evolution effects and the heterogeneously distributed reaction profile were established and verified. It was found that the pore structure of different particle size sorbents all exhibited a transition from the bimodal distribution to the unimodal distribution, which has a great influence on the dynamic reactive characteristics during carbonation. Within the defined particle size range, the carbonation reaction regimes all transform from interface reaction control into mass-transfer control, and the obtained critical product layer thickness that marks the transformation of control regime are 22, 46, and 74 nm, respectively, at 923 K. The maximum relative errors between experimental data and the simulation results calculated separately under interface reaction control (X < 50%) and mass-transfer control (X > 55%) with the effect of pore structure evolution are 12.7% and 12.1% over the defined particle size range.