(146b) CFD Modeling for Moving Bed Reducer in Syngas Chemical Looping Process

The Syngas Chemical Looping (SCL) Process is a viable way to convert coal derived syngas into both electricity and hydrogen while capturing CO2. The moving bed reducer in the SCL process can effectively convert syngas with iron oxide based oxygen carrier particles by adapting a unique countercurrent gas solid contacting pattern. Therefore, the reducer performance is of vital importance to the overall process efficiency. Thermodynamic analysis indicates that a countercurrent moving bed design enhances the gas and solids conversions in the reducer. Although thermodynamic calculation can predict the reducer conversions at equilibrium conditions, a comprehensive CFD model that takes into account the gas and solid flow behavior and reaction kinetics as well as thermodynamics is highly needed in order to accurately predict the reducer performance. In the present work, a CFD model for the moving bed reducer is developed using FLUENT. A two-dimensional cylindrical moving bed reactor is constructed with countercurrent gas solid flow pattern. The shrinking core model is adopted for reaction kinetics for individual oxygen carrier particle. The continuity equation for each species and the governing equations for continuity, momentum, and energy for both solid and gas phases are established. The comprehensive CFD model takes into account the hydrodynamics, reaction kinetics and mass transfer behavior in the reducer. Important reducer performance data such as the gases and solids conversions can be obtained using the CFD model. The CFD model will be verified by experimental results from a bench scale moving bed reducer, and be applied to assist future reactor design and scale up.