Dynamic simulation of fluidized bed chemical looping combustion process with iron based oxygen carrier

Abstract

Chemical looping combustion is a promising energy conversion technology for fossil fuel combustion with inherent carbon dioxide separation and minimum energy losses. A full understanding of the dynamic behavior is of paramount importance to successfully implement this technology at commercial scale. In this work, a dynamic mathematical model has been developed to simulate interconnected fluidized bed reactors of a 1 MWth syngas-based chemical looping combustion process with iron based oxygen carrier. The model consists of mass and energy balances equations as well as the equations that describe the hydrodynamics and heat transfer processes. The particles distribution inside the fluidized bed reactors is described by a 1.5-D hydrodynamic model. The model showed two zones in axial direction (an upper lean zone and a bottom dense zone) and a horizontal separation between core region and wall layer. Different heat transfer mechanisms have been taken into account: convection between gas phase and the oxygen carrier particles; convection of the moving particle phase with wall and radiation. The developed model was used to predict (in space and time): gas and solid velocity distribution, gas composition distribution, behavior of oxygen carrier, and temperature profiles inside the air and fuel reactor. The dynamic behavior of the chemical looping combustion process was studied by step and ramp input changes in the input gas flow rate.