Flow behavior and heat transfer in bubbling fluidized-bed with immersed heat exchange tubes for CO2 methanation

This study aims to investigate hydrodynamic and heat transfer characteristics of a BFB reactor with immersed heat exchange tubes for CO2 methanation using a two-dimensional (2D) gas-solid Eulerian computational fluid dynamics (CFD) model. A reaction kinetics model for Ni-based catalyst was coupled with the CFD model. The 2D-CFD model with the Huilin and Gidaspow drag was validated with experimental data for the bed expansion of Geldart B particles according to gas velocity. It was demonstrated that the heat of reaction was effectively removed in the BFB reactor with a 25% heat exchange area and that the reactor maintained isotherm conditions. The CO2 conversion was 92% in the BFB reactor at 400 °C and 5 bar. The overall heat transfer coefficient from the bed to the heat exchange tubes was estimated at 114 W/m2/K for an inlet gas velocity of 0.13 m/s.