A hybrid particle model with advanced conversion parameters and dynamic drag model applied for the CFD modeling of an entrained-flow gasifier

Abstract

The main focus of the current work is to establish a hybrid particle model to depict the char conversion process, taking into account the influence of pore diffusion on the carbon consumption rate. Compared to existing char conversion models, the new hybrid model uses advanced correlations for conversion parameters such as the density and diameter exponents α and β and the Random Pore Model correction factor γ, which are functions of char conversion and effectiveness factor. CFD simulation results for a Pressurized Entrained-Flow Reactor (PEFR) using the hybrid particle model are in good agreement with experimental data. In addition, the current work also introduces dynamic drag models based on the development of the shape of spherical and non-spherical particles during the char conversion process. The dynamic drag models, which up to now has been missed in calculation of particle trajectories, are examined to evaluate their influences on the total carbon conversion of the PEFR. Furthermore, the performance of ideal particle sub-models such as the Uniform Conversion Model and Shrinking Unreacted Particle Model are also studied and compared with that of the hybrid particle model. PEFR CFD simulation results illustrate considerable differences between the carbon conversion profiles obtained with these sub-models and those profiles obtained using the hybrid particle model.