Modeling oxy-fuel combustion in a 3D circulating fluidized bed using the hybrid Euler–Lagrange approach

Abstract

Results of experiments and numerical simulations of the coal oxy-fuel combustion process in an experimental circulating fluidized bed (CFB) are presented in this paper. The simulations were carried out using the hybrid Euler–Lagrange approach to model the dense particle transport in the CFB pilot installation combined with a model of the combustion process. The main aim of presented work is to demonstrate the applicability of the hybrid Euler–Lagrange technique for modeling the particle transport process in the CFB, which also includes the coal combustion process modeling. To the best knowledge of the authors, there is no implementation of the hybrid Euler–Lagrange Dense Discrete Phase Model (DDPM) approach for modeling the CFB in the 3D domain with combustion process simulations, which is available in literature. Both the experiments and numerical simulations were carried out for three oxidizer compositions O2/CO2, i.e. 21, 30, and 35% of the oxygen volume fraction. In order to investigate the numerical model sensitivity when combustion conditions change, additional tests were evaluated for case with 35% of the oxygen for three excess oxygen ratios equal to 1.05, 1.15, and 1.25. The important aspect of modeling the radiative heat transfer during the fluidization process combined with oxy-fuel combustion was also investigated. The set of numerical simulations was performed for different radiation model configurations. The numerical results were compared with the temperature profile measured within the combustion chamber of the pilot test rig.